A lot of apps will take more memory than they need so they can keep more data "live" and be more responsive when they need to perform actions.
If you ran the same set of apps on a 2GB machine you'd get different numbers.
If you ran the same set of apps on a 2GB machine you'd get different numbers.
Besides, I'll have to take your word on that, since my 4GB macbook pro has become completely unuseable due constant swapping, but it could be completely unrelated.
Which is annoying, because it leads to double-buffering.