I was in on a thread on this down in the Rumors and News forum. There is a good chance of something coming to fruition later. But, Depp is tied up on other productions through 2010. If he is interested, Bruckheimer is interested, and Disney is interested (which given the box office receipts WHY WOULDN'T THEY BE?) it is bound to happen at some point. At least that is my opinion. Disney has had their entire Pirate line revitalized by these films. Given past movies (ETA: I actually meant High School Musical, for which they just signed the cast for parts 3 & 4???) they have a tendency to beat a dead horse. Something that has become this successful is sure to get another shot. I would think the hardest part would be getting Depp and he has stated, during several interviews, he is interestedin taking this character further.
I guess in my mind it's not a question of IF, but WHEN.