I, too, like the idea of PBL. However, I've generally seen this referred to as "Project-Based Learning." In my classroom, I frequently use Project Based Learning. I am able to seamlessly incorporate content and skills into each project, and students learn organically by completing the projects. Students often say it is a nice "break" from the traditional forms of teaching, and many students discover that they learn best by hand-on, project-based learning. It is a great way to teach and for students to learn, and helps some students who have been labeled as "struggling" in other areas to discover how they learn best. I hope that I can continue to use PBL in an online format. I plan to have students divided into "support" groups to help them work through the projects. It will be interesting to see how this strategy pans out in an online environment.