A new Canon EF lens (not EF-S) to Sony NEX lens converter, with 1-Stop increase - and AF works (DPReview: pokey, but it will autofocus).
"Canon EF 85mm f/1.2L II lens becomes a 59mm f/0.9 lens on a Sony NEX..."
Other mount combos to follow: Leica R, ALPA, Contarex, Contax C/Y, Nikon F (with aperture control for G lenses), Micro 4/3 and Fuji X-mount. Other mounts to be added in the future.
DPReview mini-review, some chart and real life shots. Looks much better than one might expected (but then, Brian Caldwell designed the optics...):
Edited by scottnilsson, 01 February 2013 - 21:11 .