Let's agree that the authoritative figure is 359, since that's the number of distros on the list maintained by DistroWatch.com.
True, some distros are more distributed than others. Ubuntu, which is clearly the flavor of the month (who says publicity doesn't matter when it comes to Linux?), is out front of everything else, according to DistroWatch. OpenSUSE, PCLinuxOS, Fedora, and MEPIS round out the top five. (Since this is an enthusiast site, one must assume that Novell and Red Hat are way unrepresented, so one should add those guys into the top tier.)
The existence of some number of multiple versions of Linux makes sense, on the grounds that there are different kinds of users who need different distros? But 359?
DistroWatch's stats page has as apt an explanation for this phenomenon as you find anywhere:
"A Linux distribution is like a religion. If you've ever tried to suggest to another person that his or her choice of a distro might not be the best, then you know what I mean." [The "I" is probably site founder Ladislav Bodnar.]
Ah, so Linux is like a religion. I seem to have heard that one before. Which begs the question: Isn't one of the tenets of the Linux "religion" the belief that open source advocated are wiser than Windows users? (The other core concept is that idea that free software is somehow nobler than stuff you have to pay for.) They'd never let Linux evolve into a "giant hairball," which was the colorful way Sun Microsystems' chairman characterized Windows
Linux won't fork because the fork-er has to do too much work for no payoff: Any worthwhile improvements he makes will be absorbed into the main branch, and his fork will be discarded/ignored as pointless.
One defense-- I'm sure I'll receive comments in this regard -- is that this comment is referring to forking of the kernel rather than a multiplicity of distributions. It is indeed true that the kernel hasn't forked in any significant way, thanks to Linus Torvalds' control.
It's also true that the few deviations that can fairly be called forks are very valuable, in that they are patches or shell add-ons (the latter are not really forks) to support real time and load balancing. (Real-time Linux merits is a worthy endeavor, meriting a whole, separate discussion.)
So I'll grant readers that, if there's anything amiss with my argument, it's that I've dragged the "f" word into the discussion. I should've just said that there are way too many distros and left it at that. But then I wouldn't have been able to close with the thing I can't help but think, no matter how many times open-source supporters tell me that what they're offering is so much better than the OSes peddled by Microsoft. It's this:
There's no other way to put it: Linux is a forking mess.