According to an information, the announcement will be coming sometime in the next 30 days, but no solid date has been nailed down. Original estimates pegged an announcement in June, however Canon announcements move around pretty frequently.
There is only little info about the mirrorless camera. The most notable is mentions that it will use the same sized sensor as the G1 X, and maybe even the exact same sensor. There has been no mention of the mount for the camera, that’s probably the biggest question surrounding it.
It is also rumored to be launched with three lenses, and we will see a new mount. There will probably be some way to make the camera compatible with at least EF lenses, and maybe EF-S as well. canonrumors.com