Here are the confirmed specs, courtesy of IGN:
# An IBM PowerPC based CPU with 3 symmetrical cores running at 3.2 GHz each, packing the most-advanced artificial intelligence and physics processing available
# A custom ATI Graphics processor and more than 512 MB of memory for high definition games and entertainment applications
Don't forget that each processor has simultaneous multi-threading, aka SMT, which basically makes it possible for each CPU to do two things at once. In other words, basically 6 CPUs are at work. !!!!!. Supposedly the Xbox 360 is going to have more graphical/processing power than any computer
in the next 12 months. That's effing incredible.
Xbox-- 1 CPU @ 733MHz
Xbox 360-- 3 CPUs @ 3,200MHz (3.2 GHz)
Wow. And everyone thought the original was powerful.