A CPU beefier than anything a desktop has seen before is on the horizon. Quad Core is set to arrive with both Intel and AMD variants as early as 1Q 2007, only a year from now. Under the guise of the "Kentsfield" core at Intel and the "K8L" series from AMD, if we really do see 4-way cores from both companies it will be one of the fastest accelerations in desktop CPU technology in a long time. Conroe and AM2 are both slated for a release earlier this year, and with clock speeds not shifting much from either camp, a quad-core CPU seems to make a lot of sense. Thermal concerns definitely come in to play, here, but both AMD and Intel have been laying out plans to reduce power consumption per core and overall.
Intel is already set to go with 65nm production, and AMD is still using 90nm, so it's possible that we may see an Intel chip run cooler than an AMD chip for a quad-core setup. Hopefully AMD will be on the 65nm camp by then. Time will tell!