I've been on the edge of picking up a D90 for a while now, and it does seem like great value for the complete package. However, two things are currently stopping me.
First, you can achieve the same image quality on a D5000, which has largely the same features, but without a built-in motor (since your lenses are AF-S, this doesn't matter), and with a rotating screen, for a little less money.
Second, there is a very strong possibility a direct successor to the D90 is on its way in the next few months - so you might want to hold out either for the successor, or for the drop in D90 prices which will closely follow.
Still, if I see a bargain D90, I'm going straight for it!