"Revisited frame rate tests on a nice, low-latency, high rate CRT: 30 to 60 fps is huge, 60 to 120 fps is only barely perceptible." -- id Software Technical Director John Carmack, reviving an age-old debate.
He mentioned this some time ago too (earlier this year, late last) and mentioned that only high level gamers would notice 60-120fps, but he does admit the difference is there.
For hardcore gamers it means something, for the others, not so much...