The info comes from a man who must know: Kevin Eastman, the owner of the "Heavy Metal" franchise and co-producer of the film. Some youtube-guy by the name of rgbfilter got his hands on Eastman and wrenched him for some info. And Eastman even has a good story to share about why Fincher took the project away from Paramount:
The studio was trying to negotiate with Fincher to cut down the running time for "Benjamin Button", and said they were not going to green-light another project before Fincher complies. Guess how Fincher handled that? -- Well, definitely something you should hear from Eastman's own mouth.
The brand-new info on "Heavy Metal" is that Fincher has taken the project to Sony and production is scheduled to begin this fall under David Fincher's "executive production" reign. The above mentioned A-list directors have expressed an interest in taking on segments of the film, David Fincher included, and at this time Eastman is looking at a 2010 release date.
The really cool Fincher part of the interview starts in part II at 1:30.