The site puts it nicely:

    Almost despite himself, Linus Torvalds started a 
    revolution in September of 1991 with the first 
    version of his Linux kernel software. Since that 
    portentious moment, Linux has grown to be an 
    international economic force.

Of course, I'm one of those people who strongly feels that the more important revolution was Richard Stallman's initiation of the GNU project in September, 1983. So we also recently marked 20 years of Stallman's revolution.

I remember when I first heard about Stallman from a geek friend, around 1986. By then GNU Emacs was done. I had used the original Emacs when I was in grad school at CMU, and had first worked on Unix systems in the late 70s. I was pretty impressed by Stallman's ideas. My friend and I discussed how he was a good person. A genius. But we also thought he was a bit delusional in his GNU idea. We figured, at best, there would be a few bits of good software like a free EMACS and C compiler coming out of the project.

We were wrong. Stallman was right. And I for one, am glad about that.