It would be built on the EOS 3 frame and have eye-control and other advance features (improved AF, low light etc.) Not full frame CMOS however and street price between $3,000 and $4,000 USD.
In reply to speculations about the desirability of such a thing, there does seem to be a big gap in Canon's price/quality range between the 10D and the 1Ds, which the 1D does not fill except for those whose usage fits its high speed/less pixels trade-off. Something at around $3000-$4000 with a somewhat more professional grade body than the 10D and at least as many pixels might find a niche. Improved viewfinder coverage and magnification for example?
Nikon and Olympus seem to be working on variants of that "middle ground" too.
On the other hand, I am still not persuaded by the "digital Rebel" stories: there is probably only about $100, less than 10% of total price, to be saved by cutting down the non-digital parts of the 10D. Instead Canon can probably respond to low end competition like the Pentax *ist D by getting the 10D price down low enough that anyone wanting to pay signifcantly less will probably opt for a high end compact digicam (with better wide angle options!) instead.
