I've seen a lot or talk about the use of open source software in the public sector. It sort of seems like a gimme to me - open source software is free or inexpensive, usually results in increased security, provides more extensibility, and avoids the market dominance issue by allowing government to do business without complete reliance on Microsoft.

Here is a good resource from Gartner research, which provides an overview of open source iniatiatives in the US and internationally, and provides many links to internal and external sources for more information.