SiS has released it's new 655TX chipset for the P4 platform today. It's a DDR dual channel chipset that supports the latest P4 800Mhz HT cpu's as well as the addition of thier Advanced Hypersteaming Technology. Motherboard makers using the new chipset should be shipping this November.
Having seen a few preliminary benches from it's previous sibling the 655FX, this chipset should be able to outperform Intel's 875P chipset. It should also bring prices for P4 motherboards down to a more reasonable level.