A Different Kind of Web - edited by and with contributions from me, but mostly a collection of what other smart people have to say. Many case studies of Web 2.0 implementations in archives accompanied by longer more reflective essays about the impact of social media on archives. You can order it from the SAA bookstore and view the table of contents here.
Web 2.0 Tools and Strategies for Archives and Local History Collections has been published by the fine folks at Neal-Schuman Publishers and by Facet in the UK. SAA members can order it for a discount through the SAA Bookstore and it’s on Amazon, of course. More info, including access to the table of contents and excerpts from some rave reviews here.
I have also contributed chapters to The Future of Archives and Recordkeeping: A Reader (edited by Jennie Hill, Facet Publishers, 2010) and to Many Happy Returns: Advocacy and the Development of Archives (edited by Larry J. Hackman, Society of American Archivists, 2010). Both of those publications are also available for order from the SAA Bookstore.