I think it has indeed switched. In fact, I recently heard of the new Venice core that they're putting into their single-core processors, and I believe they're supposed to run cooler now.

I'm thinking of doing the same thing as you. If I had the money, I'd get a Shuttle SN25P, and then possibly get a 3000+ w/Venice core, while I wait for the 4800+ to come out and lower in price. I'd probably do that right now, but I don't have enough left over for a good video card. Everything else I'd probably just cannibalize from my current system.