Linux does well in the server world, and Apple get a lot of attention, but even then, between them, they account for something like 4% of OS installs.
I'm also not sure there is much need for GNU. The licenses are absolutely awful for things that claim to be free... sometimes if something is using LGPL with exceptions it will see some serious reuse (Qt as an example) but the GPL license is a great way to stop a project ever reaching its full potential due to its viral nature.