Just noticed that I posted the wrong URL for the Open Access chapter of my new book Scholarly Communication for Librarians (Chandos Publishing, Oxford 2009). Here is the correct URL: http://eprints.rclis.org/16282/.
This chapter is an overview of open access, covering definitions in depth, major types (archives and journals) and examples of major initiatives.
Many thanks to open access colleagues who reviewed this chapter for me.
If you're interested in purchasing a copy of the book, ordering information is available here.