I'm revisiting Songbird after a considerable break and what I have to report is very encouraging. First, there are now linux builds available (YAY!) so it's on it's way to become the iTunes of the Linux desktop.
Second, there is now a URL bar so setting the proxy values though is slightly shady is now possible without having to hunt down files in the mozilla profile directory. Songbird is really a great example of what can be done with Gecko using xulrunner.
The software is pretty neat in what it can do. You can browse Music blogs, listen to online radio and even play your local media files. Not sure what are the underlying codecs but I think it's VLC. It also has inbuilt search with a bunch of options ranging from Google/Yahoo to Music based domain search engines. And yes, Creative Commons is there too.
At the end of the day though this is just a browser so it can also function as your default browser though there doesn't seem to be support for tabs :( which would have been interesting as I can then consider it as a 2-in-1 application and take firefox off my desktop-app list.
Still, Songbird is definitely worth a try for those who are on the continuous search for the one-true-media-player.