"it's a little creepy that they are releasing films giving Heath Ledger top billing when, y'know, he's dead. I wonder if they'd finished principal photography or whether they CGI'd a lot of his scenes?"

Ummm, according to IMDB.com, neither.

"After the death of Heath Ledger, production was shut down for a few months. Then it was re-started when Johnny Depp, Jude Law and Colin Farrell agreed to complete Ledger's role. The film's fantasy premise, and some clever rewrites, let the actors play a man whose appearance changes as he travels between imaginary worlds."