Wow, how times have changed: Variety is actually picking up stories first posted on Ain't It Cool News. And it turns out to be true!
I actually sat on this one for awhile because, hey, it's AICN, but it does appear that Terry Gilliam has cast Johnny Depp, Colin Farrell and Jude Law to pick up where Heath Ledger left off in his last film, The Imaginarium of Doctor Parnassus (Farrell confirmed it in a recent interview). Seems that the fantasy flick deals with alternate dimensions that Ledger's character travels through, and in each one he will appear as one of the other actors.
Admittedly, this could be a tough one to pull off, but if it works (and if anyone could do it, it's Gilliam), it would be a fitting tribute to Ledger.
UPDATE: It is now officially official: Terry Gilliam confirms the unique casting of the three stars.