If you're interested in the replication of great schools--one of the key innovations of the charter mechanism--check out this informative paper by the folks at the Center on Educational Governance. ????It has lots of good facts and figures and some interesting history lessons and insights.
This 2007 report from the great team at the Charter School Research Project, though a bit older, is thorough, thought-provoking, and worth a read.
Finally, this 2004 speech by Joe Graba is as fine an explication as I've ever seen on why a new schools strategy is an essential component of education reform.