Intel dual-core support for hyper-threading
In a recent post I referred to Intel's hyper-threading technology, but mentioned that I wasn't sure whether the new dual-core processor chip supported hyper-threading for each core, but I just read a post on an Intel web feed ("Intel® 955X Express Chipset") that in fact refers to the new 955X Express Chipset as having the "Ability to manage four software threads simultaneously". In other words, HTT supports two simultaneous threads in a processor, so double that for dual-cores.
Now how to design system software and optimize your application software around that architecture is another story.
I saw a reference on some Microsoft blog that implied they were seeing a 20% benefit from HTT with a specific application.