!OK, so this isn't old - it is a bit of help for PPC users - HERE and NOW. The New Twitter API (2013) has been rough on older Macs.
So this is an AppleScript launcher for WebDesktop that logs automatically into twitter.com and sets it as a fully-functional Twitter-wallpaper on your desktop! A bit of a hack, but a good one ;0)
Your Icons float above it and you can even touch the desktop like normal, without switching apps. But with a quick Command+TAB, you can be Tweeting, Re-Tweeting, Scrolling up and down and managing your Twitter account.
The interface updates every 5 minutes (adjustable). Toggle launching (click once to activate, and second time to deactivate).
Installation is very simple. Just open in AppleScript editor, save your login info and you are good to go! Also, includes a delay adjustment for older Macs/slower connections (Info in the Read Me).
** NOTE: Some have worried somewhat about older WebKit browsers and security, but WebDesktop does not store cookies, bookmarks or preferences, so should be relatively secure (especially, if you only use it in connection with Twitter, as instructed).
OSX 10.4/10.5 - Dual CPU G4s/G5s recommended.