So, Borderlands turned out to be a successful little title for Gearbox. And we all know what that means in this business, don't we kids? That's right....ssseeeeeeeqquuueeellssss.
Speaking with VG247, Gearbox's Mike Neumann said "Everyone here loves the franchise, and it seems like the public is really coming back with praise and love. So yeah, if everything makes sense, Borderlands 2 seems like a no-brainer to me".
Hardly an official announcement, but then, it's hardly surprising, either. Game sells -> game is popular -> game gets sequel isn't exactly a revolutionary turn of events.