Okay, let me clarify that: David Goyer is definitely pitching a Sandman movie, and Badass Digest is reporting that The Dark Knight's Rises' Joseph Gordon-Levitt is somehow involved. It's possible that JGL wants to direct it, but it seems much more likely that might play Dream in such an adaptation (or both, hell).
This is way too early to really even speculate about, but you should recall that 1) Warner Bros. loves themselves some David Goyer, seeing as he's written all three of Chris nolan's Dark Knight movies and Man of Steel, 2) I'm sure Warner Bros. would be equally excited to have Joseph Gordon-Levitt involved, and 3) President of DC Entertainment Diane Nelson said not four months ago that a Sandman adaptation was at the "top" of their movie to-do list.
On the other hand, there have been plenty of DC movie ideas — including a few by Goyer himself — that never made it past the announcement stage, so I wouldn't hold your breathe just yet. But man, I think JGL would be a pretty inspired choice to play Dream. Hmm....