The list price of the 10D is $2000, but I see it selling for $1400. The list price of the Rebel is $900, so...
1400 * 900 = 2000 * X
1260000 = 2000X
Which leaves us with...
630 = X
So, if the pricing ratio stays the same, the new camera (body only, lense sold seperately) will sell for $630. It will use all the old EOS (EF) lenses, and the new EF-S series, which give you wider angles on the digital camera.
When I see point and shoot digital camera's going for $800 street price for 5mp, and lower quality pictures, I wonder how this will shake up the digital market in all areas.
You can read about the new camera here and here.