The question is whether Canon intends to make 2007 purely as the year of the 1D Mark III, or as a double bumper harvest year by introducing the 1Ds Mark III as well.
40D, I suspect, will sneak in later this year as yet another "upgrade" with much ado 'bout nothing features (10mp, Digic3, sensor cleaning).
The 5D Mark 2, given the present celebrate-the-1series atmosphere is likely to be a show stopper if it comes out. So very, very likely to be next year's trump card to show who's yer daddy when (or if) Sony/Nikon comes out with full-frame bodies.
If you need full-frame digital today, just get a 5D and put your L lenses through their paces.