I noticed that the WPILib control system documentation for 2016 is available here. (I am surprised that this available considering it was released last year just minutes before kickoff.) It appears that most of the pages have been updated to include information about control system changes this year, and tutorials have been updated for installing the 2016 FRC Update (Although the download links are for 2015). It also appears many other tutorials have been updated and improved.
It will not be released until kickoff. However, the WPILib source code is publicly available if you want to look through the changes (or use our mirror). There are other resources available in various places too, you just have to look for them.