So when will PCs catch up? The console vs. PC debate has always been a balance, consoles would always debut more powerful than PCs, then PCs would catch up and surpass consoles during their ~5 year lifespan. The difference this time around is that the desktop CPU industry is going through a big of a transitional period, it may take a little longer than usual for desktop CPUs to be able to outclass (in all areas) their console counterparts. As far as GPUs go, by the end of this year I'd expect to see 360 and PS3 class (or faster) GPUs offered for high end PCs. By the time the PS3 is released, I would say that the upper mid range GPUs will offer similar (or very close) performance.
The truly limiting factor will be the transition to 65nm on the desktop, the faster that can happen, the quicker the PC will regain its power advantage. But despite any power advantage, this next generation of consoles will definitely be powerful enough to tempt away some PC gamers...at least for a while.