Which Simpson's character will come out?

Well, it looks as though one of the regulars on The Simpsons will be coming out of the closet this January:

During a comic book convention in San Diego last weekend, the creators of "The Simpsons" promised the show would take on same-sex marriage, and one of the characters would come out of the closet.

"We have a show where, to raise money, Springfield legalizes gay marriage," producer Al Jean said in a quote published by the BBC. "Homer becomes a minister by going on the Internet and filling out a form. A long-time character comes out of the closet, but I'm not saying who."

I know, I know, Smithers is the obvious choice.  But, when has the Simpsons taken the obvious choice?  Did any of us think it would be Maude Flanders who got killed off? (I certainly didn't.)  So, who's it gonna be?