I don't understand why people think the EF system would be suitable for a mirrorless camera. The flange back distance is huge compared to Sony's E Mount or micro 4/3. And as traveller said that equals a thick non pocketable camera and I've already got one of those (my T1i).
I'm really disappointed in the direction Canon seems to be taking with non-L primes. Can't we just have ring USM updates of the 35 f/2, the 50 f1.8 and the like? No, we've got to add IS to slower, short focal length primes and jack the price to $800.
Again, I guess if someone wants a tiny lens for FF the 40mm makes some sense, but for crop? No thanks.