i think it depends on price.

i have the D90 and am extremely pleased with it. not saying i don't want to upgrade to the D7000, because i'm a bit of a gadget junkie, but if you can find a D90 for a really good price, i'd go with that.

i've been doing portrait shoots lately, as well as night time low-light stuff, photographing my animals, my D90 gets SO much use and i haven't found any harsh limitations.

.... hmmm i just did a search on Futureshop and Bestbuy to compare prices between the D90 body and the D7000 body, and the D90 is no longer on there. I wonder if they're going to be hard to come by, soon.