Yup, I'm also looking to upgrade to either a D300 or D90. Currently using a D60 with dual kit lenses, and the AF-S VR Micro-Nikkor 105mm f/2.8G IF-ED. I still can't decide whether to get the D300 or D90.
Besides the D300 having more AF pts, faster shutter speed, and the D300 supporting timelapse recording, what other notable features does the D90 have? Price difference between the 2 bodies is about $1k!!