I can't find Canon putting it's latest innovation into a model where neither most users don't care about it nor it is neccessary. As far as I recall the 1D series where the ones to receive the new processor with (I think) the 50D beeing an exeption (1D III came shortly after)
True - and as has been pointed out, most P&S don't need anything more than the DIGIC IV at the moment.
Things probably point to a new processor in a 1DV or 1DsIV. I doubt we would see the 5DIII before at least one of these is launched.
If the rumours about a full frame 1DV are true, then an interesting approach would be for Canon to launch the 1DV, which would give sports shooters and studio pros what they need, but allude to something bigger coming, and launch the 1DsIV a few months later, then a 5DIII after the dust has settled. Of course, we are all just speculating. If you add a 7DII after the 5DIII, that gives Canon a year's worth of high end DSLR announcements and the opportunity to create a lot of hype.