Alright, here is a thought if nobody has tried this yet. Let's approach it from a matter of process of elimination. As this is a publicity stunt, an "Iconic" character is going to have to be someone that most people will have heard of, rather than someone known mostly to serious comic book readers. Basically someone like Doctor Fate is unlikely because your average person is liable to have absolutly no idea who the heck Doctor Fate is for it to have any meaning. Nor is it someone that the gay community could really get much cred for being able to tout, since few people (including the gays themselves) will probably have heard of it.
For the sake of simplicity I think we can eliminate Green Arrow, Superman, and Batman right off the bat. The reason is that I don't think DC could retcon those characters as gay if it wanted to. Those rights have all been sold to multiple parties. We have Batman movies planned up the wazoo (apparently the next movie series after the Nolanverse concludes has been being planned), Superman is apparently up for another movie attempt and allegedly another TV series as Smallville concluded, and apparently there is a Green Arrow TV series on the way since the character was fairly popular in Smallville. Even if some of this doesn't materalize it's all been being planned out for years, and represents tons of potential money. While the whole "the hero is now gay" thing will genrate publicity, it could play havoc with these plans, and create problems with the guys who hold the rights. After all if they are writing a whole series of TV shows about Green Arrow, playing him up for the ladies (I guess part of it was girls liked the character in Smallville, even if this is probably going to be a differant version) and spending tons of money getting it ready, suddenly outing him as gay and having all these comic shop posters of him smootching guys or however they plan to promote it could play some serious havoc. I could even see lawsuits over that kind of thing... and it would be a big mess. The same applies to all three of those. Basically if DC has been shopping the rights around out there, or already sold them, and you've been hearing serious discussion of new IPs around the character, DC isn't going to do this with that character.
Heroes I'm pretty sure DC doesn't have any rights to in current circulation for TV, movies, etc... are The Flash, Aquaman (he was in Smallville, but the plans for a TV show apparently didn't pan out, and I don't think anyone holds that option or had plans), Cyborg, Martian Manhunter, and some of the lesser Green Lanterns are all potentially up for grabs. I'm pretty sure that despite the horrible performance of the Green Lantern movie, the rights are still being held since I believe they grabbed it for multiple movies, anticipating it being the next big thing. So if they have a gay green lantern, it's not likely to be "The" Green Lantern (Hal Jordan).
At any rate, following this chain of logic, who else can people eliminate based on how this could affect IP deals DC is already involved in? It's especially relevent is a project was under works or the rights had been sold/brokered long before DC's annoucement.
Whether you think it's bigoted, and wrong or not, in your mind if a character being gay could say affect a box office performance and get a company like Warner Brothers pissed off enough to try and go after DC for money, chances are it's not happening.
