Well, that was quick.

With Neversoft/Activision’s Guitar Hero: World Tour looming on the horizon in October, laden with the powerful Guitar Hero brand, a slew of deep gameplay modes and a collection of “instruments” that appear noticeably superior to their Rock Band counterparts, the team at Harmonix/EA/MTV Games announced that Rock Band 2 would release in September for the Xbox 360, one month prior to Guitar Hero: World Tour and only 10 months after the original’s release in November of last year.

“With the original Rock Band, the focus was on innovation,” Harmonix CEO Alex Rigopulos told The Associated Press. “With Rock Band 2, the focus is on perfection of the experience. We’ve had a year to listen to our fans and build out the scope, depth and polish of the experience, so it feels like a second-generation band game.”

Only they haven’t had a year in the marketplace yet, and while I’m not privy to the details of Rock Band 2’s development cycle, sports games generally go a year between releases and change very little in most cases. In an exclusive preview to IGN, Rock Band 2’s lead designer, Dan Teasdale, discusses the game in very little detail, saying little more than the game is deeper and better.

“For fans interested in hardware, the second-generation peripherals are an amazing step forward from the first-generation guitar and drums,” said Rigopulos. “The instruments make huge strides in both fit and finish as well as features and functions.” We’ll have to wait until Rock Band 2’s July’s E3 showing to find out exactly what Rigopulos is talking about, because the guitar that IGN shows in its coverage is simply a re-dressed version of Rock Band’s current Stratocaster mock-up.

Curiously, PlayStation 3, PlayStation 2 and Wii versions will be released at some point later in the year, according to Harmonix. Why the Xbox 360 gets the pole position for one of the biggest releases of the year is unknown, but “Microsoft has been a great partner for Rock Band,” says MTV Networks Music Group’s president Van Toffler. “It’s just so easy to download the content using the Xbox 360 system. It’s evolved into a great marketing partnership as well. They’ll really blow it out for us.”

Most importantly, Rock Band 2 will have retroactive compatibility, meaning that any songs downloaded for the original Rock Band will be immediately playable in the sequel, and Harmonix insists that the in-game Rock Band Music Store is designed to function in any Rock Band game, so those that choose not to upgrade won’t be penalized with a lack of new content.

And with over 80 master tracks shipping on with Rock Band 2, the genres involved in that content look to be expanding. Teasdale spoke to IGN about the Rock Band Music Store’s downloadable content (DLC), where over 15 million tracks have been downloaded thus far, saying that “You’d be hard pressed to justify Jimmy Buffett and Disturbed on the same disc, but the great thing about DLC is that we can push the boundaries of what players experience.”

Says Toffler, “I believe we’re going to see global online competitions where bands performing throughout the world will compete against each other. I’m personally excited to open up the genres of music to country, hip-hop and R&B. We’ve just scratched the surface, really.”

They’re both right. Rock Band has sold 1.3 million units to Guitar Hero III’s 2.5, but in many ways, that’s comparing apples to oranges. When Guitar Hero: World Tour ships in October, both music-game franchises will be band-centric, and expanding the scope of the game (and the types of music found within) stands to land Rock Band 2 a lot more customers, assuming they do things right.

By the middle of July, we’ll know if 10 short months was time enough to re-invent the wheel.