So I actually snuck a new version of Songbird for Mac OSX PPC up to the server about a month ago. The dmg includes both Songbird and some of the extensions, including a working version of the Shoutcast plugin. At times I've had some instability with this version, so as always be sure to backup your configuration inside ~/Library/Application Support/Songbird2. (This directory is from memory, since I've mothballed my PPC Mac for the moment.)
Give me some feedback, if you use it. I'll probably turn on the Mac once in a while to spin off a new version if folks still want me to. But I got tired of recompiling the rest of my dev binaries to stay up to date via NetBSD's pkg-src and I don't particularly care for what I've seen of Lion and I had a spare dual-core AMD machine sitting around, so I've swapped out the Mac for an Arch Linux box. And for someone who's been using a Mac since the 512Ke and Plus with those wretched recessed Torx screws and groovy signatures engraved in the shielding, I'm surprised at how happy I am with XFCE and a sprinkling of apps from both KDE and Gnome.