Shizowa San updated the SF4 dev blog today with announcement regarding the Tokyo Game Show. According to her, both a ps3 and 360 version will be playable and both will have Dan and Fei-long as well as a third character (probably Cammy).
Shizowa San also added that the trailer of the Street Fighter: The legend of Chun-li will debut during the show.
Tokyo Game show will be held this year from October 9th et 12th.
Source: SF4 dev blog