Today Microsoft and Red Hat announced a visualization interoperability deal. Red Hat is the most popular open source brand on the server and a leading Linux distro; Microsoft needs no introduction. The two companies will cooperate based on an open set of standards, and stay away from restrictive patents--the detail that is said to have torpedoed Novell with the open-source community.
Wikipedia will be using the Ubuntu Linux distribution to power its sizable server infrastructure, report numerous sources. The popular online knowledge repository will try to create a homogeneous server environment in an attempt to reduce complexity and costs. The Linux flavor of choice is the Hardy Heron 8.04 long-term support version.