This switch-over from Red Hat to Ubuntu has been taking place over a period of several years. According to Brion Vibber, CTO of the San Francisco-based Wikimedia Foundation, Wikipedia made the move because the "mix of things, some Red Hat 9, some Fedora, several different versions," made it harder and harder for Wikipedia's tiny five-person IT staff to maintain Wikipedia's approximately 400 servers.
So Vibber and the rest of the IT staff shifted to Ubuntu so that it could make "our own administration and maintenance simpler." In short, they "decided that we want to standardize on something."
That's always a smart choice. People like yours truly can play operating systems like hop-scotch, jumping from one to the other, but that's no way for even the smallest of companies to handle operating systems and platforms. I'm surprised that an operation like Wikipedia, with its millions of daily readers, never mind the load of the eternal editing and re-editing of stories managed for so long.
While there's a great deal of similarity between the various versions of RHEL and Fedora, the differences between them would prove very difficult to work with. In my experience, it's more trouble to work with multiple similar systems than it is with multiple systems with clear differences between them. With the former, you're always making small, annoying mistakes that add up to slow, painful work days.
So why isn't Wikipedia moving to RHEL or Fedora? Gordon Haff, an analyst at Illuminata Inc. pointed out that it would have cost them more money. Wikipedia's staff already has the in-house expertise they need to run a major Linux data center so they don't have a pressing need to pay for RHEL's support. This kind of cost savings is one of the reasons why I think we'll see more companies, including ones currently invested in Microsoft's Windows Server, moving to Linux and other open-source programs.
Of course, if you're moving to Linux for the first time you'll need support. Companies like Canonical, Novell, and Red Hat will be happy to sell it to you. However, once you have the hang of it, there's no reason you can't go it on your own. After all, that's what Wikipedia is doing and if they can pull this off with a complex Web site with multiple-millions of hits per day I really think you can probably do it with your business servers. I mean you do want to save anywhere from a few thousand to a few tens of millions of dollars by switching to Linux don't you?