Depp, but no Knightley as "Pirates of the Caribbean 4" is Confirmed

A fourth installment of the Pirates of the Caribbean franchise has been confirmed by Disney. The date so far, is looking like it will be released in 2011, but that's not official right now. What is official is that Johnny Depp has signed on to once again play everyone's favorite pirate, Capt. Jack Sparrow. Other sources have confirmed that Keira Knightley, who has portrayed Elizabeth Swann in the three Pirates films will not be returning. She was quoted by M&C, saying:

"I think it was wonderful and an amazing opportunity and those films were just extraordinary and I was extremely lucky to be a part of them. But no. I think my pirating days may be over."

As far as the plot is concerned, there was hint at the end of At World's End, of a possibility of the pirates searching for The Fountain of Youth (Pirates of the Caribbean: The Fountain of Youth?). On the other hand, AICN received word from a source, saying:

In regards to PIRATES, two dramatically conflicting assessments about how a fourth film might be approached have been making the rounds. Some 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.) Not sure how I feel about either notion, to be honest. Not sure if I even care to see a fourth PIRATES film at all.

Only time will tell as we eagerly await the next couple years of hearing anything further about it.