Paul Rudd is officially the star for Marvel's first Phase 3 (movies released after Avengers 2) film, Ant-Man. Directed by Shaun of the Dead's Edgar Wright, Ant-Man will take a more comedic approach, following the exploits of a man who can shrink to the size of an ant. His co-hort and girlfriend, The Wasp will likely make an appearance, and it's rumored she will be played by Rudd's former co-star Rashida Jones.
The movie is set to release summer 2015. Also, be prepared for likely eventuality of Rudd joining Avengers 3.