Intel's 4GHz Prescott processor using LGA755 with 1MB L2 cache is targeted for Q1 2005.
The 580 has an 800MHz system bus and will be released round about the same time as Intel's 670, 660, 650 and 640.
These chips are really Gallatin core processors - they have 2MB of cache and an 800MHz front side bus, as we've reported previously.
A quick look at the crib sheet reveals that the 670 clocks at 3.80GHz, the 660 at 3.60GHz, the 650 at 3.40GHz and the 640 at 3.20GHz. These are Extreme Edition chips - Intel is obviously pushing these as top end processors, but because megahertz don't matter any more, the clock speeds are obviously irrelevant.
At launch time, the 670 et al won't have the no execute bit implemented.