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.
We are working on second edition of PostGIS in Action 2ed for availability sometime in Early 2015. Early purchase review (MEAP) is now available for Second Edition: All 17 chapters now available on MEAP with code and data download on PostGIS In Action Edition 2 Chapters. With MEAP you can get chapter updates as we write/update them and get the final polished copy at release time in both E-Book and Hard-copy form. Each purchase includes all E-Book versions including E-book version of 1st edition.
PostgreSQL: Up and Running, 1st Edition 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. We are hard at work on the second edition of PostgreSQL: Up and Running, 2nd addition as well. The 2nd edition is feature complete and E-book draft version is available now direct from O'reilly. Hard copy will be out 4th quarter 2014 and with focus on PostgreSQL 9.3-9.4.
© Leo Hsu and Regina Obe 2014