The Software Freedom Law Center (SFLC), who describe themselves as a "provider of pro-bono legal services to protect and advance Free and Open Source Software (FOSS)", today published a very useful in-depth primer that introduces the reader to the legal issues related to FOSS. See it here.
This web-based guide was written by members of SFLC's staff to cover "a variety of legal topics and their practical application to free software development". These topics include copyrights and licensing, organizational structure, patents, and trademarks.
Its a very helpful primer that is potentially helpful to newbies and advanced practitioners alike.