I don't think apple will give two speedbumps to the pro line within two months, so don't get your hopes on a 1.4 ghz g4 or a g5 in march-april too high.
I can be wrong, of course, but i don't recall Apple doing this ever before.
Why would Apple make the Dual out of thier fastest processor? Right now the Quicksilver lineup is 733, 867, and dual 800. Didn't the last lineup have a dual 550 while the top of the line processor was a 733?
Don't count on the Duals being made from the top of the line processors.