In 2006 the 12 provinces of the Netherlands developed Flamingo, software for managing and viewing geographic maps. They plan to publish a second tool, called CDS (Central Data and Service environment) based around INSPIRE standards. These applications were developed as open source based on well-known open source tools including Postgis and Deegree, which are supported by the Open Source Geospatial Foundation (OSGEO).
The provinces estimate that since 2009 they have saved € 4.5 million by working together and using open source software solutions for their GIS applications.
The provinces have created a foundation to support the Flamingo community. Next year, they plan to pursue a similar community development approach for CDS.
The provinces are now taking a similar approach for other applications that have been developed to be compatible with the European INSPIRE directive, a set of standards, many of which are also Open Geospatial Consortium (OGC) standards, for sharing geospatial data about the environment.
A presentation on this initiative was delivered at the INSPIRE conference this year in Florence.
Thanks to Derek Oswald for pointing me to this.