people said the same thing about quads. and in less than a year they have gone from enthusiast only parts that offered no real performance, to the defacto standard in most rigs and a recommended spec for most game releases.
you can say my idea is 'silly', but the fact is right now i cannot encode a video for my ipod at the same time as gaming without a performance hit (at least when i play crysis, or BC2).
when i get a 6 core not only can i do my encoding in the background (which will save me a lot of time) i can even leave every other program i normally shut down, running in the background. hell, i could even leave EVE open in the background to do some mining, and still play another game without bad performance.