Books:

Open Source Licensing by Larry Rosen (Prentice Hall 2004) - This is the first best book on open source licensing.  While I may not agree with Larry on every conclusion he draws, this is definitely a worthwhile book.  It is available in printed edition at most bookstores, but you can find an on-line copy available under the Academic Free License version 2.1 by clicking the title above show your appreciation to Larry by buying a printed edition.

The Open Source Alternative: Understanding Risks and Leveraging Opportunities by Heather Meeker (Wiley 2008) - This is a brand new book on open source licensing and related legal issues by my good friend, Heather Meeker.  I have, as yet, not read the book in its entirety, but what I have read is quite good.  As with Larry Rosen's book, I don't agree with every conclusion Heather draws, but defintely a book any lawyer dealing with open source should have.  The book is only available in printed edition. 

Articles: 

An Analysis of the Eclipse Public License (version 1.0) and GNU General Public License (version 2.0) and the Interaction of Works Licensed Thereunder by Mark Webbink (2008) - A look at the way code licensed under the EPL and GPL can be associated.

Licensing and Packaging for Virtual Appliances by Mark Webbink (2007) - A discussion of the concepts relevant to packaging open source virtual appliances and packaging open source software generally.

Exit and Voice in Free and Open Source Software Licensing: Moderating the Rein over Software Users by Greg R. Vetter (February, 2006 University of Houston Law Center)

Open Source Software: Free Provision of Complex Public Goods by James E. Bessen ( 2005, rev. 2006)

Accessing and Contructing Knowledge Through Core Software Infrasturctture: The Case for Free Software as Democratic Principle by Mark Perry and Brian Fitzgerald (2005)

A Guide to Open Source Software for Australian Government Agencies - Australian Government Information Management Office (2005)

Open Source and the Legend of Linksys by Heather Meeker (2005)

"Infectious" Open Source Software: Spreading Incentives or Promoting Resistence by Greg  R. Vetter (Fall 2004, Rutgers Law Journal)

The Collaborative Intergrity of Open-Source Software by Greg R. Vetter (2004, Volume 2, Utah Law Review). 

Software That Lasts 200 Years - Thoughtful article by Dan Bricklin (of Visicalc fame) on the merits of open source 

Understanding Open Source Software by Mark Webbink (2003) as published in the Journal of the New South Wales Society For Computers and the Law.  This is a relatively short piece I wrote to help others understand the basics of open source licensing.  It has been translated into numerous languages and republished around the world.

Affidavit of Eben Moglen on Progress Software vs. My SQL AB Preliminary Injunction Hearing - Eben Moglen (2002)

Open Source Software Licensing by Steve H. Lee (1999)

Videos:

The McGowan Forum - Web 2.0 Technologies and Participatory Democracy  November 5, 2009

Mark Webbink and Alan Cox on the Red Hat Patent Promise  March 17, 2008

Mark Webbink on GPL3  November 9, 2007

Mark Webbink on the Red Hat Patent Promise  November 9, 2007

Mark Webbink on Software Patents  October 19, 2007

Eben Moglen's "Be Very Afraid" Talk on Microsoft and Patents  May 14, 2007

Links:

International Free and Open Source Software Law Review - A law review providing articles and commentary about open source and open source related issues.

OpenSource.com - Exploring the application of open source principles to other worlds.

Free Software Foundation - Home of the GNU licenses and projects.

Free Software Foundation - Europe - The European group dedicated to free software.

Open Source Initiative - Home of the  open source definition and OSI certified open source licenses.

Software Freedom Law Center - A not-for-profit law firm rendering legal advice to open source projects and enforcing open source licenses on behalf of the copyright holders.  You can also find educational and advisory content in the Resources section of this site.

Groklaw - Source of information on the SCO Group lawsuits against IBM, Novell and customers and the Red Hat lawsuit against the SCO Group.

European Commission Open Source Observatory - News and information about FLOSS development in the European Union 

Free / Open Source Research Community - An MIT maintained website containing a wide variety of papers written about FLOSS 

Free and Open Source Software for those in Germany - FOSS für die in Deutschland - Discussion about licensing, activities, and initiatives.

Freedom Task Force -  The Freedom Task Force is a legal infrastructure project that helps individuals, projects and businesses understand Free Software and the opportunities that it presents.

GPL Violations - Want to understand more about what constitutes a GPL violation, some examples, and enforcement actions?  This is the place. 

Guide to legal Issues in Using Open Source Software - From the New Zealnd Government 

IBM Open Source Portal  

Open Content - Source for the Open Publication License. 

Open Source Legal - A website of open source legal information provided by the Gessmer Updegrove law firm.

Open Source Law - A website maintained by Brendan Scott of Australia.  If you want to get a view of open source from a common law country other than the U.S., this is a good place to start. 

Open Source Law Blog - A blog maintained by the Morris Manning & Martin law firm. 

Open Source Software Development - A wide range of papers from the Institute for Software Research (U. Cal - Irvine) regarding FLOSS 

Proceedings of the First International Conference on Open Source Systems (Genoa, Italy 2005) 

Why Open Source - David Wheeler's thorough discussion of why open source makes sense, including qualitative measures.