Not that any of them were topping the charts with major motion pictures prior to 2003, here is a listing of their current work per imdb.com:
sean penn:
Why Men Shouldn't Marry (2004) (announced)
21 Grams (2003) (completed) .... Paul
Mystic River (2003) (completed) .... Jimmy
It's All About Love (2003) .... Marciello
You'll Never Wiez in This Town Again (2003) .... Himself
tim robbins:
Code 46 (2003) (post-production) .... William
Mystic River (2003) (completed) .... Dave
"Queens Supreme" (2003) TV Series (episode "Flawed Heroes")
susan sarandon:
Whale in Montana, A (2004) (filming)
Ice Bound (2003) (TV) .... Jerri Nielsen
"Children of Dune" (2003) (mini) TV Series .... Wensicia
Manatee: The Forgotten Mermaid (2004) (in production) .... Narrator
martin sheen:
Jerusalem (2003) (post-production)
Commission, The (2003) (post-production) .... Deputy Attorney General Nicholas Katzenbach
Absence of Malick (2003) (V) .... Himself