After hours of troubleshooting, a disconnected anomaly was all I could find. For months my Canon MP620 printer worked fine under Leopard and Snow Leopard. My wife's MacBook printed well wirelessly. But, one day her MacBook printing just stopped working. I went through the usual suspects: reboot machine, reboot printer, reinstall drivers, manually clean out drivers and reinstall etc. Nothing worked.
Both Mac OS X Leopard and Snow Leopard come with a paltry set of solid colors for desktop backgrounds. This is easily remedied with ImageMagick (available for install through the MacPorts Project) and a quick hack. The script below generates all the background images for web-safe colors that should then be immediately available for use under the Solid Colors selection in the Desktop and Screen Saver System Preferences. You can copy and paste the script into Terminal, but you'll need to be a system administrator for it to succeed because it writes the images into "/Library/Desktop Pictures/Solid Colors".