For anyone wondering what this vim/tmux thing is about, what it looks like and what it can do (and seeing the questions in the rest of the comments, there are a few), click the link to that book and check the video. I was only vaguely familiar with tmux (as in I knew it's some sort of `screen`) and this really made it clear to me.

As soon as I put Linux on this machine I'll give it a try, too :)