Since Canon EF mount lenses usually do not have a manual aperture control ring, it either doesn't make sense to mount those to other camera systems (with the exception of Samyangs) or involves a serious amount of costly electronic support. At the moment there actually is only one simple solution I am aware of - the Conorus/Metabones EF - E mount, which is also the cheapest, but seems to support the most features.
The following list is a summery of mounts with electronic control and focused on cine applications. There are seperate lists for cine targeting EF-MFT adapters as well as adapters to mount EF lenses to mirrorless cameras (incl. Canon EF-M, MFT, Sony E and Fuji FX).
Birger Engineering Canon EF Mount (2008) is a fully electronic mount supporting all relevant functions of EF lenses, especially including iris and focus. It is either controlled by PC / MAC or by a Viewfactor Impero (see below). The mount communicates all lens data to the camera (iris, focus, zoom). It is widely known amongst RED ONE users, which features a PL mount, but it is also used by Allied Vision to mount EF lenses to their Nikon F and C mount models of the Prosilica GE and GX series. Allied also state compatibility with all Canon EF, EF-S, Tamron DI and Di-II lenses.
Birger is reported to work on a Micro Four-Thirds and Sony NEX adaption. A first presentation of a prototype was spotted at the NAB 2011, a Sony F3 version was announced to start shipping in November 2011.
The Viewfactor Impero is a controller unit originally made for the Viewfactor Inclino (an external motor drive to control iris, zoom and / or focus). Birger adopted it to control their EF mount. The Impero can be set up to work wired as well as wireless. As of 2008 it required a modification of the Impero's Bluetooth radio unit as well as a modification of the COM port (from CAN to RS232). In 01.2009 Viewfactor started to ship the Imperos with a compliant radio unit by default, and as far as I get it, there is a cable produced by Birger to prevent the port modification (by simply crossing wires, that usually would not cross). That cable is also required for firmware updates. The Impero is powered by a 9V battery. The production seems to have been stopped in 2010. A new batch is announced.
Metabones EF - E mount a.k.a. Conurus Canon EF Lens To Sony NEX Smart Adapter (2012) is an adapter to mount Canon EF lenses to Sony NEX cameras. The adapter was tested to work seamlessly with Sony NEX-3, NEX-5, NEX-5N, NEX-7, NEX-C3, NEX-FS100, FS700 and NEX-VG10 (other models are supposed to work as well, though not tested). It supports EF as well as EF-S mount (EF-S might result in some soft vignetting due to differing crop factors of EF-S (1.6x) and NEX (1.5x)). Support for electronic aperture control via camera as well as proper EXIF data from lens is given (aperture values are rounded up / down though, depending on the camera). IS functionality was tested with different lenses and should work with adapter firmwares v1.02 and newer (factory update required for older firmware versions and granted free shipping, but those were only shipped during the first few days after initial release). The IS is powered by the camera. The adapter features a button to fully open the iris for manual focusing and bright frame preview as well as it offers a tripod screw mount. There is no AF support. E-M lenses work flawlessly. Metabones has published a list of lenses tested with the adapter. The mount goes for 400$.
In the second half of 2012 the adapter was updated to Version II, then featuring a detachable AS-style quick release plate, a round opening with anti-reflection surface and a power saving mode which reduces iris and image stabilization actuation during image preview. AF support was then given for Canon lenses majorly released since 2006* and seemingly a few third-party lenses** as well. The AF performance was not as fast as with Canon D-SLRs. According to Metabones it's slower than EOS M system or Sony NEX with their LA-EA2 adapter (for Sony A mount lenses), but claimed still faster than A mount lenses mounted using the Sony LA-EA1 adapter. For all other lenses the new version will just work like the old one. Version I Conurus adapters could be (factory) upgraded. For the FS100 and FS700 AF will work in Still Mode only, not in Movie Mode.
In 2013 EF - E Mount Mark III was released by Metabones. Additionally to the above features Mark III supported the NEX VG900 (full frame cam) and seemless switching between EF and EF-S lenses (auto-crop). From this version on, Conurus was no longer mentioned nor did they post updates about the product on their site any longer. Still the mount - including the Speedbooster version - has its own subforum within the Conurus forum structure, where it is stated that "Conurus has an agreement with Metabones to supply the electronic technology exclusively to Metabones. So, unfortunately Conurus will not be able to sell the electronics to anybody else." (conurus 2013-04-24)
Mark IV followed in 2014. It features refined "internal structure" (coatings, electronics?). Otherwise the features list reads as / appearance looks like before.
*These include the Canon EF-S 10-22mm f/3.5-4.5 USM, EF-S 17-55mm f/2.8 IS USM, EF-S 17-85mm f/4.0-5.6 IS USM, EF-S 18-55mm f/3.5-5.6, EF-S 18-55mm f/3.5-5.6 IS, EF 22-55mm f/4.0-5.6 USM (although much older), EF 28-90mm f/4.0-5.6 III, EF 70-200mm f/2.8L IS USM II, EF 70-200mm f/4.0L IS USM, EF 70-300mm f/4.0-5.6L IS USM, EF 70-300mm f/4.0-5.6 IS USM, EF 85mm f/1.2L II USM, EF 100-400mm f/4.5-5.6L IS USM and EF 300mm f/2.8L IS USM.
**Third-party lenses supported are Sigma 17-70mm f/2.8-4.0 DC OS HSM (AF issues still reported at the long zoom end), Tamron 24-70mm f/2.8 Di VC USD and Tokina 11-16mm f/2.8 DX AT-X PRO.
MTF Effect (2011) consists of the so called Control Unit, which is wire-coupled to an electronic mount for Canon EF lenses. IS is supported. Mounts are available for MFT, Sony E (NEX and FS-100) and Sony FZ cameras. The original FZ mount was called F3 mount, since with its release in 2011 the PMW-F3 was for long the only camera with this mount (the PMW-F5 and F55 were announced in late 2012). Using the FZ mount results in a magnification factor of 1.5x. The control unit comes with illuminated display to show the current focal length and aperture (both in realtime, even during zoom with lenses not featuring constant aperture values). Aperture can be adjusted in 1/8th stop increments by turning a knob. Mark I of the control unit was powered by AA power cells lasting for a day of shooting. It will automatically shut down when idling to save energy. The only incompatible lens named (as of 2012) was the EF 1.2/85. There was no reason given, but it features E-M, which might be the reason.
In 2013 Control Unit Mark II was released. It is now powered by an external power source via D-Tap or 4-pin Hirose and size and weight were reduced.
In 2014 they aditionally added an EF to AJA Cion mount to their selection. The AJA Cion uses a standard PL mount and comes with a removable front mount plate. The MTF adapter has the front plate build-in, so the adapter will only fit the Cion, not other PL mount cameras.
About pricing ... they charge 650£ for the Control Unit and 350£ per mount (460£ for the Cion). Alternately they also offer dumb mounts, which still go between 200£ and 275£ (415£ for the Cion).
Redrock Micro LiveLens Active Lens Mount (2009) was the Redrocks' first active lens mount for Canon EF lenses. You actually can't mount it to any camera directly, it's made to be mounted to the M2 Encore or M3 Cinema Lens Adapters (camcorder DOF adapters), which are mounted to the filter thread of a camera mounted lens. The lens mount controls the aperture of EF lenses (same working principle like their MFT adapter). It's powered by an external battery pack (standard 9V 6LR61 (1.2A max.) or IDX Endura 10s (14.8V, 6.3A)).
The RrM LiveLens Active Lens Mount cannot be mounted to MFT cameras ... check Dedicated Lenses > Adapting EF > EF to MFT for the LiveLens MFT version.
Wicked Circuits' Smart Mount (for PL mount) uses an external controller to control the lens (see below). It supports EF and EF-S and is supposed to work with any EF lens, even 3rd party (... in theory ... not all lenses were indeed tested). The mount seems to be powered by the controller. It was presented at NAB 2010, first reports go back to 2008. A few samples seem to have made it out of the factory. It was announced to become RED certified (which would have meant a warranty preservation). Same size as the Dumb Mount.
The Wicked Circuits Smart Mount Controller (Standard Version) supports electronically transmitted manual control of focus and iris and offers remote control either using a Bluetooth device (supports Win Mobile, XP - 7, OS X and iPhone) or any standard Sony compatible IR remote. It saves multiple focus positions and recalls them in any order with adjustable speed settings. It is powered by the camera's AUX or some other external 12V power source, weights 113.4g and has a size of 128 x 73 x 20mm. It was presented at NAB 2010 as well.
The production state of Wicket Circuits is uncertain, the website still shows a "coming soon" for the controller and wasn't updated since ages. There is a praxis report by Vincent Laforet, so it does exist. There also is a dumb mount version, see RED ONE listing.