Seeing as Sigma DP2, Olympus Pen, Panasonic GF1/GH1, Leica X1, and Samsung NX are making waves. I suspect that Canon is working on a digicam with a APS-C sized sensor for enthusiasts that want a small compact camera with dslr level image quality.
Here are my suggestions and wish list.
Metal and like G10 series in size (a bit bigger due to sensor/lens) and ergonomics. I really like that rotating ring at the base of the lens mount like in the upcoming s90, and would like to see it here as well. I suspect that the body will be solid black as is the current G series. But a red ring by the mount would be nice and along the lines of a Canon L lens in terms of look. Of course it should have a little flash built into the body.
12MP CMOS sensor with 1.6x crop factor like the Rebel XSi. I'd like to avoid 15/18MP for less noise if possible. But if Canon wants to trump others with a class leading higher MP of 15, so be it.
I thought long and hard about this. I don't think EF-EF-s mount would be good as it may make the camera/lens unit too big. I actually like the idea of going with a fixed zoom like what's on the G10/11 series. Of course b/c the sensor is bigger, the lens will be bigger but I think if they design a lens specifically for the body, they can work on a small one as found on the Leica X1. I'd guess for a 35mm f2.8 or maybe a bigger but more versatile 24-60mm f2.8-4. In lens IS would be nice as well.
Viewfinder: The optical one in the G series is nice or an EVF version of it would do. I personally would favor an optical based system. Why not an accessory based one to go over the hot shoe? That's an option but would work only with a prime IIRC. Plus it's more money. The built in viewfinder would trump the others in terms of feature (not including the Panny GH1 and Samsung NX).
To keep the body as thin and light as possible, I'd like to see a 2.7-3 inch non moving LCD with 930,000 dots. The 3 inch 930K dot seems to be the standard, so that should work.
Live view contrast based of course.
Buffer: I suspect b/c of AF being slower and the body being smaller, that the fps and buffer may be less. I think 3 fps for 6 shots RAW would be more than plenty for this type of camera.
Since Canon is coming into the game late, I think they would have to trump others in terms of price. Just like the Canon s90 trumps the similar Panasonic LX3 ($429 vs $499), I'd venture to guess right around the Olympus Pen's price range of $799. If they offer more features and the market is hot, then $799 would be a good starting point. If the market is saturated (especially if Nikon joins in) then I suspect the price may be even lower as the market matures and the competition increases. Maybe $749 to $699.
Just all guesses and dreaming of course.