Andrew Miller, consultant for the Buck Institute of Education, published a nice article on getting started with Project-Based Learning in Math. Included are some thoughts on when projects are appropriate and how PBL fits in well with the Common Core.
I also recently found a Maryland teacher blog with a great deal of content (specifically for math and engineering on the high school level) but with one important lesson to remember: moving toward PBL is a process. Mr. Yates, who teaches in Maryland, states he began with projects interspersed when the opportunity was there (time, resources, and alignment.) After several years of teaching in this way, he has moved to a new goal of building the course around a themed and scaffolded series of projects.