Since Apple still doesn't think that supporting a free, fast, unemcumbered, lossless audio codec is a good idea, I had been using Play on Tiger. Unfortunately, it is broken on Leopard. Version 0.2 doesn't start anymore at all. The good news is that the author is working on it. In fact, the latest builds (using r1057 at the moment) at least start and seem to, well, play, but I don't seem to be able to import anything into the Play library, for example.
As good as Play will eventually be on Leopard (and it is likely to remain a much more lightweight alternative to iTunes), Apple really needs to support FLAC. Who needs the Apple Lossless format anyway? So go Apple, put an engineer on it for a few days and support FLAC already.