Got Snow Leopard today and decided to upgrade. Install went smoothly and took about 30 minutes. The only glitch was after it was done I got that strange blue tinge screen, but a reboot corrected that. Here are the steps to upgrade:
Insert DVD and run the Upgrade installer.
Once upgrade, go to www.adobe.com to install the latest flash player since the one with Snow Leopard has a security hole.
--- The next are optional ---
Install XCode from the installer disc.
Install macport 1.8 for Snow Leopard
Follow the instructions to update macport packages: https://trac.macports.org/wiki/Migration
Tracking status of macports on Snow Leopard: http://trac.macports.org/wiki/snc/snowleopard