Today Capcom announced Ultimate Marvel vs Capcom 3 for November 2011, an updated version of Marvel vs Capcom 3 which came out in February. So far the only officially announced new characters for the updated version are Strider (Capcom), Firebrand (Capcom), Ghost Rider (Marvel), and Hawkeye (Marvel).
Joystiq noticed that art for character profiles was on Capcom’s web server and was able to download the full list of new characters. Capcom has since taken them down, but it seems likely this is the final lineup.
Capcom: Strider, Firebrand, Vergil, Frank West, Phoenix Wright, Nemesis
Marvel: Ghost Rider, Dr Strange, Nova, Rocket Raccoon, Hawkeye, Iron Fist