There may be multiple Avengers video games in the works, according to TQ Jefferson, the VP of Games Production at Marvel. In an interview with The Hollywood Reporter, TJ mentioned Marvel hoped to reach different types of gamers, on different types of platforms.
The facebook game, Marvel: Avengers Alliance, is just one game of "multiple video game touch points." I'm not actually sure what "touch points" are but it sounds like we're going to get more Avengers games. Whether we'll see a movie tie-in on the consoles or a version of the facebook game for iOS still remains to be seen. Read the quote yourself and see what you think:
"We just launched Marvel: Avengers Alliance on Facebook; which is just the tip of the iceberg. This is the first in a much larger effort to support the Avengers franchise across not just one but multiple video game touch points. The Avengers are bigger than just one game, and we’re planning to allow consumers to enjoy The Avengers regardless of their preference in gameplay style or platform. Look for more announcements in the weeks to come."
Source: Hollywood Reporter