The big news is that, according to Aint it Cool News, 'Pirates of the Caribbean 4' is most definitely going to happen!
"Indications suggest the film's story would be far more contained than its predecessors, allowing for a budget-friendly downsizing. On the opposite end of the spectrum, there's been unsubstantiated talk that a fourth film would go the other way completely...think in terms of ultra fantastical (dinosaurs, Jules Verne-esque floating fortresses, etc.)''
So will Depp be involved at all? Only time with tell. Rumours are that Pirates 4 will not be coming now till 2011.