Avengers

Looks like there will be an Avengers film on the way.

At the end of Iron Man, Samuel L Jackson appears playing Nick Fury (inspired casting!). In Hulk, we have another similar taster.

Apparently Avengers will unite Hulk and Iron Man with Thor and Captain America.
Whether there will be solo films for Thor and Cap first, and the 5th film will sequel them both, we'll have to wait and see.