IGN let the cat out of the bag in the early hours of Monday morning — Rock Band 2 will be hitting the Xbox 360 in September and the PS3, PS2 and Wii before the year is out.

Sure, we all knew it was coming, what with over 3 million bundles sold thus far across every platform, more than 15 million paid DLC downloads and dozens of awards from names like Wired, Ars Technica and the Academy of Interactive Arts & Sciences. Why, EA would be crazy not to fashion another one post-haste, and we’d be crazy not to scream for another installment. Plus, Harmonix needs another contender to help defend their title of “King of Band Games” from up-and-comer Guitar Hero: World Tour.

So now that it’s official, what do we know so far?

First of all, DLC will be both backwards- and forwards-compatible. Rock Band tracks will work perfectly in Rock Band 2, and Rock Band 2 DLC will work just fine and dandy with the original title.

“Why should I buy Rock Band 2 if the DLC works both ways?” you ask. Well, Harmonix has been paying careful attention to the suggestions and concerns of their forum goers and everyday players, so there are a few new and interesting features we can expect, even though nothing’s been explicitly revealed:

• A killer set list, featuring over 80 disc songs! - “The biggest and most diverse soundtrack ever featuring some of rock’s most prolific acts, comprised entirely of master recordings,” says the press release. Yahoo! News remarks the list “will include more female-fronted bands and artists who have never contributed tunes to a music game.” Bands already rumored to be involved: Turbonegro, Bad Religion, AC/DC, Sublime, Testament and Cake.
• Changes to the navigation and multiplayer interfaces. - “One of our biggest focuses of the design team has been to make the game ‘party safe,’” says lead designer Dan Teasdale in an IGN interview. Sounds like we’ll have an easier time switching instruments in Band World Tour and Band Quickplay. Speaking of World Tour…
• Online Band World Tour. - Teasdale again: “I’m pretty sure John Drake (Harmonix PR Coordinator) will hit me if I confirm or deny anything, but I can say this: We’ve taken almost everything people have asked for in Rock Band and added it to Rock Band 2, as well as including some ‘first time ever’ features. Our World Tour campaign mode is no exception to this.” Considering it’s been one of the most requested features on the game’s official forums, I see no reason why it wouldn’t be in place already.
• “Quieter, more realistic, and more reliable instruments.” - Oh, and your already well-worn drum pads and fret buttons will be compatible, too, naturally. But why would you want to use those old things? Take a look at the new guitar! That’s right, ladies and gentlemen: wood-grain finish.

• More character and band customization options. - The IGN screenshots definitely show off some new threads, so your dreams of clown wigs, prosthetic noses and sword-shaped guitars might just come true!
• “New ways of experiencing your music library.” - Solo, goof-off modes for the instruments? Setlists structured on albums, bands, genres? Ways to avoid soul-crushingly difficult DLC in World Tour’s random gigs? Who knows? Well, we know for sure there’s “something targeted explicitly towards players that want to sing and play guitar.

Looks like we’ll just have to wait for more concrete information. Shouldn’t be long, though, since E3 is right around the corner, and Rock Band 2 is expected to debut there.

Finally, a little bonus joy! Long ago, the DLC wizards at Harmonix promised the seminal Who record Who’s Next. As the whole of the internet now knows, that’ll be quite impossible, since an entire side of the album’s masters was stolen from the Who vaults. GASP! Fret not, everyone, because a highly recent news item at the official Who website reveals your consolation gift: a “Best of the Who - Rock Band Edition” collection of DLC coming July 15, coinciding with the VH1 Rock Honors celebration of the band! What does this collection include? 12 masters, that’s what, even some from their Live At Leeds album! More on this development in the week after next’s installment of Faking the Band!