I just found this....
Did everyone else know Michelle would be in the Bob Dylan movie also?
Brokeback duo doing Dylan
Posted by Clint Morris on May 24, 2006
Real-life duo, and “Brokeback Mountain” co-stars, Heath Ledger and Michelle Williams will reunite on “I’m not there”, a new film about legendary musician Bob Dylan.
Ledger has stepped in at the 11th hour to replace originally cast Colin Farrell, says Production Weekly.
Directed by Todd Haynes, it’s essentially thoughts on the life of the man, where seven characters embody a different aspect of the musician's life and work. Christian Bale, Cate Blanchett, Richard Gere and Julianne Moore also star. Actress (!) Charlotte Gainsburg (“21 Grams”) is also said to be playing Dylan, at one point in the film.
Interestingly, Ledger told us in January that he’d be taking this year off, so that his wife could work. Looks like a live-in babysitter is in need.
http://www.moviehole.net/news/20060524_brokeback_duo_doing_dylan.html