KIPON just announced they will be releasing "soon" an electronic adapter so we can use our Canon EF glas on Micro 4/3 and NEX cameras.
I've already got their adapter for EOS to m4/3 with manual aperture ring control and it's a must if you have the Olympus OM-D E5 and need some longer distances. It's manual focus but it's very easy to control since Olympus got a zoom function that actually works and make manual focus a sweat.
KIPON or do an ebay seach for it has there are plenty of them for different kind of lenses.
Let's wait and see the availability of the new ones and also for what prices are they shipping in.
-- Press release --
KIPON developed electronic adapters through the co-operation with
Japanese engineers,using Canon EF mount lens on NEX or m4/3 mirrorless
cameras, through the dial ring or button to control the iris of original
Canon EF lens, let those who bought mirrorless cameras can enjoy the
Canon EF lens.
Listing specific dates and prices to be determined.