After 5000 music-lovin' I/O attendees warmed up Google's servers, it appears that the company has now finished its presumed installation of four zillion exabytes of new hard drive capacity. We're exaggerating, obviously, but probably not by much -- we've received a flood of tips today (as well as an invite amongst ourselves) noting that Music Beta is finally being opened up to Earthlings in the "real world." Specifically, Motorola Xoom owners. In case you've forgotten, that entitles you to free (for now) access to a cloud storage locker where 20,000 of your hits can be saved and streamed. Curious to know if it's worth the time to upload? Have a peek at our in-depth preview right here, and be sure to let us know if your invitation has come through in comments below.