it just doesn't seem enough of a leap.
I think that this is the problem that both 360 and ps3 will face. What exactly is the killer reason for upgrading, other than for upgrades sake? 360 have a reasonable answer with their media centre, and online offerings. Although I still struggle to see the mainstream appeal of this : if you have a PC, you can do many of the same things already.
I don't doubt that Sony will win out (or at worst have a close tie) in this generation, purely from a brand thing, but there isn't really a unique selling point for ps3, other than the software. And that's what always wins me over - I wait until I see the games for a year, then pick the platform with the most games that I want.
Which is why I recently upgraded my PC.