It's not coming out 'til 2013 and is presumably being written now or has just recently been written... so Wonder Girl could be in it. Yeah, I'm guessing the 12 heroes are the main 6, Zatanna, Red Arrow, Aquagirl (Tula), Tempest (Garth), Rocket and Wonder Girl. I may be wrong, but I figure that the teen heroes from the Comic-con playing cards stand a good chance, and that Wonder Girl is most likely to be selected out of any other teen heroes who may be appearing on the show.
"Are you the dreamer or merely part of someone's dream?" - The Mad Hatter.
B:TAS - Perchance to Dream.