A collaborative effort between Conurus and Metabones, this conversion mount will even give you electronic aperture control (though there's still no autofocus).
Conurus and Metabones have teamed up to create a new lens adapter, one which allows you to put your canon EF-mounts onto a Sony NEX body. Set to go for $399, the Smart Adapter manages to bring an admirable level of electronic communication between the body and lens. EXIF data transmits accurately, electronic aperture control works, as does image stabilization, and PASM shooting modes. The only glaring deficit is autofocus, which is something you rarely see in lens adapters.
If you're really into adapters, you can stack the Smart Adapter with the already existing Contax N to Canon adapter, and jury rig Contax 645 lenses onto a Sony NEX body.
We'll be interested to get our hands on one to see just how well it can deliver on all those promises.