Coming Soon has a story from MTV Movies with comments from Jerry Bruckheimer who talks of where they really are with the Pirates sequels:

Producer Jerry Bruckheimer is negotiating with Geoffrey Rush to star in a third "Pirates of the Caribbean" movie. "That's if there is a third one," Bruckheimer said. "We're hoping to start shooting [the second and third movies] in March, but we're waiting for a very big check from Disney." Bruckheimer said talk of Keith Richards playing Johnny Depp's father is premature, although Depp, Orlando Bloom and Keira Knightley are all signed on to return, along with the director and writers from "Curse of the Black Pearl."

How unreliable sources can be and quickly stories can spread. Looks like some of the earlier stories aren't as concrete as we would have hoped, and no mention of Chow Yun-Fat either.

Reading between the lines here, it does look like they are go on number 2, and depending on casting and that big cheque, there may just be the third too.