A recent blog post on the SongBird blog states that the Linux version will be discontinued:
After careful consideration, we’ve come to the painful conclusion that we should discontinue support for the Linux version of Songbird. Some of you may wonder how a company with deep roots in Open Source could drop Linux and we want you to know it isn’t without heartache. We have a small engineering team here at Songbird, and, more than ever, must stay very focused on a narrow set of priorities. Trying to deliver a raft of new features around all media types, and across a growing list of devices, we had to make some tough choices.
SongBird got 4% of our ongoing "Best Linux Music Player" poll votes so far and even though many consider it a resource hog, it's still sad to see such an application leave the Linux world.