UPDATE: Images of the camera body (without lens attached) have surfaced on the net with what looks a 3:2 aspect ratio sensor (providing they're not photoshopped), suggesting Canon has chosen APS-C instead. If that is the case, it's almost certain to be the same sensor as found in the EOS T4i / 650D (though the camera will be without phase detection AF). Another image shows an 18-55mm EF-M lens, more-or-less confirming Canon has adopted the APS-C format for its mirrorless range.
Canon are set to launch a new mirrorless range next week, according to reports on the web, the first in the EOS M range is believed to be the camera shown above. The model shown features an interchangeable 22mm f/2 STM pancake lens. The STM lens uses a stepper motor for 'smoother' focusing operation (though by all accounts in its current form it's not noiseless, thus at odds with the intended video market). AF is performed by contrast detection (CD) sensors embedded in the CMOS imaging sensor, and was debuted in the recently announced EOS Rebel T4i / EOS 650D. As for for the size of the imaging sensor, we believe it will be smaller than APS-C, most likely a 4:3 aspect ratio 14.3 megapixel CMOS measuring 18.7x14mm, as used by the current G1 X. If so, the 22mm lens shown above would be the equivalent to a 40mm. At this moment in time it's all conjecture, however the new camera system is said to be revealed next week, most likely as early as Monday.