Wikipedia is switching from Redhat, Fedora and other Linux distros to Ubuntu in order to unify and standardize their system…
Since its hard to maintain 400 servers with Five-ITs-Per-Server (I think…) with different distros as Wikipedia servers…
Bottom line, they choosed Ubuntu (I think… And you can read it at the end of the link’s article below) because switching to Redhat would cost more…
Here’s the Computerworld related link.