I've seen the this kernel documentation project emerging a while ago. It's truly amazing how open source can be used to write a book.

Awsome work!

Unrelated to the post, but another illustration of a great open source book effort is the Stacks Project on algebraic geometry and algebraic stacks: http://stacks.math.columbia.edu/.

What I've loved about following along on this book is that all I need to do to get a new chapter is 'git pull' .. its truly the future of publishing. ;)

You may want to browse the rendered version of it: https://0xax.gitbooks.io/linux-insides/content/Timers/timers...