Iron Man director Jon Favreau and an a-list of writers have joined Robert Downey, Jr. on Cowboys and Aliens, according to the Hollywood trades.  The latest version of the script for this film, which has been in development for over a decade, is by Damon Lindelof, executive producer on Lost, and writing duo Alex Kurtzman and Roberto Orci, who wrote Star Trek, both Transformers pics, Mission Impossible III, and Fringe. 

Downey has been attached to the film since last summer (see “Iron Man Finds a New Home on the Range”). 

Production is expected to start in 2010.