We've had leaked betas of Google's Music 3.0 app for Android for what seems like time eternal now, but Google has finally chosen to make the app public. At least part of it, that is. It sports the same interface as the beta we've all come to know (and love?), but lacks one key feature, mysteriously: a settings menu. That's probably owing to the fact that the previous betas we've seen all contained sync (Google Music) options in the settings menu, and unless you're a beta-invitee (don't worry, none of us have gotten ours yet, either), these options will presumably remain hidden and otherwise inaccessible.
You can grab it on the market now (it will not show up as an update!).