Intel not only showed off its next generation 45nm Penryn processors at Intel fall IDF 2007 during CEO Paul Otellini keynote, they showed a three-week old second generation 45nm Nehalem processor running Windows XP.
What's notable about the Nehalem processor is that not only does this processor improve upon the execution engine in Penryn; it also includes a brand new memory architecture called "QuickPath" (AKA CSI) that will vastly improve the memory subsystem to allow the chip to scale multiple-cores. Each Nehalem processor will have 4+ or 8+ cores with two threads per core which means it will be able to run 16 execution threads in hardware. Current x86/x64 processors from Intel and just recently AMD have 4 cores and a total of 4 execution threads so Nehalem should be a massive jump in thread count, scalability, and performance. [Update 3:00PM - I got a clarification that the first version of Nehalem will be 4 cores in 2008, the second version of Nehalem will be 8 cores on a single monolithic die in 2009.]
Pictured below is Glenn Hinton (Chief Nehalem Architect, Intel Fellow) along with CEO Paul Otellini demonstrating one of the first Nehalem processors that barely got "taped out" a month ago. The PC booted Windows XP and played back an audio file with a synthetic computer voice saying "I am Nehalem, I am three weeks old".