We are working on second edition of PostGIS in Action 2ed for availability sometime in late 2013/early 2014. Early purchase review (MEAP) is now available for Second Edition. With MEAP you can get chapter updates as we write them and get the final polished copy at release time.
Our most recent book
PostgreSQL: Up and Running is out in both E-book and hard-copy. You can order hard-copy now from Amazon or Kindle
or hard-copy or e-Book from O'Reilly .
PostGIS is used by organizations large and small and has garnered a lot of commercial support. Its ease of use, unmatched performance, feature set, scalability, ease of deployment, and ability to integrate in most any environment makes it a no-brainer solution for most GIS work involving high end analytics and integration with other business processes.
These are sites using PostGIS that are publically accessible
This uses pgRouting (which means PostGIS as well), OpenStreetMap
Below we have a list of links to case studies on how it's currently used.
© Leo Hsu and Regina Obe 2012