[happypeter]

I've been a git super fun for years. But I have to say Hg is much more friendly to newbies. My reason for git's popularity is:

The code is out of the hands of Linux kernel team, so you can believe that git will work well. And the fame of Linus and later github also count.

[giulianob]

Github attracted a lot of the Ruby developers. They are extremely vocal on the web which I think is what made Github and Git so popular. I personally prefer Hg over Git as well due to friendlier syntax but Git hit it off a lot better w/ that vocal OSX community.

I don't know many people who use Windows that like Git. The ports were buggy for a long time and the best visual tool, SmartGit, isn't free. Mercurial which has TortoiseHg which is excellent but I hear is painful to get running on OSX (maybe this has changed). Mercurial is fairly popular still though. I think a lot of people use it but not many popular articles get written about it the same way it does about Git.

[happypeter]

Yes, ROR people talked a lot, on web, that also counts.