The Associated Press reports that the sequel to Rock Band will be released in September for the Xbox 360 and Playstation 3 by publisher MTV Games and the game developer Harmonix. Here’s the official press release: LOS ANGELES (AP) – “Rock Band” is ready for an encore. A sequel to the play-along music game that redefined the genre last year will be released first for the Xbox 360 in September, according to publisher MTV Games and developer Harmonix. “Rock Band 2″ will feature a new variety of instruments, online modes and songs, and will allow players to import their previously purchased “Rock Band” tunes. “With the original ‘Rock Band,’ the…