A build of Google Music, specifically 4.0.1, has been leaked from a “lost Nexus Prime.” While the back story is no doubt shady and convuluted, let’s just skip ahead to the updated app shall we?
The latest version of Google Music has a revamped interface, more options, better controls, and overall more polish. You’ll likely notice a few subtle movements that have proven to utilize space more efficiently. Some of the bigger differences are the inclusion of a search key (Ice Cream Sandwich has no dedicated hardware search key) as well as more options and details on tracks currently playing.
You may encounter an error when trying to install the APK. If so, it is likely that you need to uninstall the Music app you currently have. After which the install should work.
To uninstall the Music App:
Go to settings, applications, scroll to the music app and uninstall.
More screenshots and download just past the break.