You can bank on more plank. According to the Hollywood Reporter, Disney has already set sail on making a sequel to ''Pirates of the Caribbean: The Curse of the Black Pearl,'' which opened just a week ago. In fact, the Reporter says, Disney anticipated the film's success (it topped the box office this weekend with $46.6 million and had taken in $78.1 million as of Monday), having made advance deals for sequel participation by most of the principals. There's no story yet for the sequel, but Johnny Depp, Keira Knightley, and Orlando Bloom will all return, as will director Gore Verbinski, producer Jerry Bruckheimer, and screenwriters Ted Elliott and Terry Rossio. Let's just hope this doesn't give Disney ideas about making sequels to other Disneyland attractions-turned-movies; no ''Country Bears II,'' please.