There's a lot in the latest issue of the International Free and Open Source Software Law Review.
Andrew Sinclair profiles the BSD license.
Neil Brown discusses the license obligations for GNU GPL 2.0 and 3.0.
There's a piece called "Copyright in Open Source Software - Understanding the Boundaries."
It's 108 pages and worth at least skimming if you use or build open source software. You can download the entire issue here (PDF).