To clarify, that test that GregW posted compares the old Pilot Sport (directional tread) with the P-Zero Nero.
The PS2 is superior overall to the tires in that old test.
To give Pirelli its due, the new P-Zero (not Nero, not Rosso, not System, just plain P Zero) is a monster in terms of grip and handling. I have driven this tire on the track and came away very impressed. Not as quiet as a PS2, and the handling feel of the PS2 is still hard to beat, but the new P-Zero was faster around our track. Note the incredible wet traction in our test results.