The visionary lies to himself, the liar only to others - Nietzche
As a matter of fact, 2MB cache will help a lot those users whose apps (including games and such) have a lot of big cache-friendly pieces of code and data, but probably not the data-streaming intensive stuff. I do expect to see speedups anywhere from 2% to 20% depending on the application, maybe some more if using multithreading/multitasking (large cache can keep in code / date pieces from more threads).
However, this doesn't seem to be a new CPU in reality - after all, Intel is doing very well with its XeonMP 2.8 GHz 2 MB cache CPU, and how much effort does it really take to repackage it for the 3.2 GHz / 800 FSB desktop with less stringent thermal and reliability requirements than the big iron, anyway?
Intel would gain a lot with this move. If, touch wood, there are problems with Prescott, a large-cache Pentium4 part will provide some buffer against large-cache Athlon64 (i.e. rebadged Opteron) parts. At the same time, enormous extra benefits from the economies of scale would further reduce the identical die XeonMP manufacturing cost, helping Intel compete better on the quad-CPU server front as well. Interesting move? I think so. Let's see how the beast performs in real! µ
See Also
Pentium to the Extreme: Part Two
All IDF coverage so far