Over the last six years, Riot Fest has become another reason to be proud of the Chicago music scene: The annual fall celebration of punk rock old, new, local, and otherwise has become the second best festival in town for adventurous music fans, right behind Pitchfork.

But today’s announcement of the “largest lineup ever” this October 5 to 9 is as much a cause for concern as a reason for celebration, for a couple of reasons.

For one thing, the fest’s official name is now “Red Bull Riot Fest,” the result of a partnership with the highly caffeinated energy drink announced last August and already in effect for the 2010 festival.

Yeah, yeah, I know: Corporate sponsorship is an unavoidable fact of life in the new millennium, stop whining and get over it, or just try to ignore the ubiquitous branding like many music lovers claim to. But it still means something in the D.I.Y. punk-rock underground, and avoiding these kinds of deals with the marketing devil is what used to distinguish a community event like Riot Fest from a shopping-mall celebration such as the Vans Warped Tour.

There was supposed to be a difference. But is there anymore?

Red flag number two would suggest not: Top billing among this year’s headliners goes to Weezer, which—despite its many merits—is in no way, shape, or form a punk band, and it never has been.

The rest of the bill largely represents Riot Fest’s typical mix of older punk acts and up-and-comers, including Social Distortion, the Descendents, X (doing the classic-album shtick, playing “Los Angeles” in its entirety), Youth of Today, Suicide Machines, ALL (Scott, Chad and Dave), Helmet, D Generation, Down By Law, the Business, Strike Anywhere, the Tossers, Macabre and Nachtmystium (bringing a little more metal to this year’s mix), the Flatliners, Flatfoot 56, the Menzingers, Banner Pilot, the Pavers, Reverend Peyton’s Big Damn Band, Shot Baker, the Copyrights, Cheap Girls, Larry and His Flask, Chinese Telephones, the Crombies, the Holy Mess, Van Buren Boys, Neutron Bombs, the Infected, and others to be named soon, including an allegedly big announcement coming on Friday.

“The final headliner announcement is very special for me personally, and almost needless to say, it’s something that I never thought would happen,” Riot Fest founder and majordomo Michael Petryshyn said in today’s press release. “We thought that this deserves its very own separate announcement and I’m happy to say that we’ll be doing it with a few close friends that you might know this upcoming Friday.”

Let’s hope this booking makes more sense than Weezer. But there are two more signs that Riot Fest may be jumping the shark.

Petryshyn always has been ambitious—check out my interview with him in 2008, where he made it clear that he planned to expand to other big cities—but with Riot Fest moving on to Philadelphia on Sept. 24 (with East Coast headliners the Descendents, Dead Milkmen, X, Plow United, Hot Water Music, Naked Raygun, Suicide Machines, Weston, and Samiam), and the promoter trying to book more shows at the dreaded Congress Theatre (the same press release announcing the Red Bull deal last August trumpeted Petryshyn’s new position there as “Head Talent Buyer for General Market and Rock”), there’s plenty of cause to question quality control.

“Because of the growth of Riot Fest, I’ve been offered talent buying jobs recently in other markets; however, it meant that I would have to give up Riot Fest, which I would never do because of the expansion we’re looking at in the next several years,” Petryshyn said last summer. “I prefer to stay independent, and when [mercurial Congress owner] Eddie [Carranza] approached me about the position and stated that I have their full support, it was an offer I was waiting to hear for the past several years. With that said I’m excited about helping make the Congress Theater one of the premier and most respected venues in the Midwest.”

Well, without a serious investment of capital, the Congress is and likely will remain an awful-sounding dump just a few short steps away from being condemned. Much bigger and better-funded promoters than Petryshyn have tried and failed to elevate the place: He follows in the footsteps of both the Live Nation Death Star and Lollapalooza promoters C3 Presents. And to date, outside of Riot Fest, he’s garnered the most attention at the venue for the aborted, over-priced, and exceedingly controversial Chuck Berry gig in January. (See Dave Hoekstra’s report in the Sun-Times here.)

Will Riot Fest fall prey to corporate compromise and over-expansion? Let’s hope not. Meanwhile, multiple-day passes and individual tickets for the 2011 Chicago shingdig go on sale Friday at 10 a.m. (top price for access to all events and venues: $145) via www.ticketfly.com.