While I was building and testing, I decided to take a screen capture for ya'll. Something for you to check out while you're waiting for the unofficial contributed build.

Songbird on PPC OS X 10.4.11
click on the image for the larger size

Yes, I've got it working on 10.4 and yes, I've got shoutcast running with mashtape pulling artist info from last.fm (in the background you'll spot my PPC7450 optimised build of the nightly Firefox 3.2a1 and the always open Terminal.app running another build of gst-plugins-bad)