I’ve been working with GIT more and more lately. It seems like it’ll make complex projects with several simultaneous branches a lot easier to work on. I just wish there were some really good easy to use graphical clients for non-engineers. Something like Versions for SVN/OSX would be great.
If you’re looking for a book, go with the Pro Git one. I originally bought the oreilly book and was disappointed.

Yeah, I switched from SVN to Git last year, and I’m really happy with it. I totally agree though, it’s designed by engineers, for engineers.
I use SmartGit for OSX and I’ve been very happy with it. For the most part I just use eGit in eclipse, but for non-eclipse IDE projects, SmartGit works very well.
A graphical client like tortoise GIT for Windows?
http://lmgtfy.com/?q=tortoisegit
it’s no versions, but i’ve heard good things about gitbox, if you’re on snow leopard.