Let's preface this piece with two points: 1) No official Rock Band 2 release date has been set for any console. 2) No official Rock Band 2 release date has been set for any console. Clear? Let's do this.
MCV reports (via Spong) that "a handful" of North American retailers have listed the release date for Rock Band 2 on PS3 as "November 23rd -- just a month after the October 19th release date." Cutting through several bits of minutia, we don't know where this October release date comes from as Harmonix reconfirmed to us today that the Xbox 360 version releases in September.
We did check with the fine folks at Amazon who said their information comes "directly from the vendor." Meaning that current information has the standalone game of RB2 releasing Sept 14, the "Special Edition" with the instruments is available for both Xbox and PS3 on Oct 19, along with the PS3 standalone version of the game. But, let's be clear, once again: No official Rock Band 2 release date has been set for any console.