The City of Chicago migrated to Red Hat in order to reduce costs and improve support, performance and scalability. The city has already saved more than $250,000, and is reducing server hardware, maintenance and operating costs as a result of Oracle's certification and support infrastructure on Red Hat.
For the City of Chicago, information technology (IT) is an integral part of the government's processes and services to the city's nearly 3 million residents. City officials, led by Mayor Richard M. Daley, have embraced a Transparent Government initiative and are committed to running an open, responsive and fiscally responsible government. As a result, the city's information systems department is committed to putting technology in place to help the government meet its operational objectives.
http://www.redhat.com/about/news/prarchive/2006/chicago.html