The volume of posts for PBL Camp is fantastic! I thought I would start this discussion for science folks looking to connect and ask questions. I'll jump in too.
I think PBL is a powerful way for students to actively inquiry about authentic issues with an authentic audience! As you work on your project, keep in mind ways that you can facilitate student "cross-talk" as they develop their ideas. Also, consider having students create a product(s) that have an audience beyond your classroom.