Don't want to curb your enthusiasm but I'd like to clear some things up (No, I am no MLG representative, just some pessimist).
It is no "vote", as the OP put it. With your vote you can show support for a suggestion to improve the MLG Pro Circuit without any kind of guarantee somebody will listen to you. It is also not "currently" running, the forum is in place at least since January and seems to be a rather general feedback forum. It is not primarily in place to request games.
Placing your votes will do no harm but don't get overexcited. I doubt the MLG will pick up TF2 for their Pro Circuit as 1) it does not provide the viewers like LoL or SC2 do (5,000 concurrent viewers for a match are absolutely bombastic in Europe and America, for example. In SC2, LoL, DotA 2 some of the pro gamers only need to go live with their stream and reach that number within a minute) and 2) because the TF2 scene is not professional enough and has no organisations backing up their teams to send them to an international event three times a year for $10,000 minimum.
