Mauricio, item list to be included in the book is rather complete (especially taking under consideration that you can't include everything).
Here are bit of (in my opinion) interesting points but maybe they are already in:
- events (boundary and intermediate) - especially timer and message events for intermediate and timer and error for boundary
- tooling - knowledge agent and Guvnor with Designer would be great too
- maybe a brief introduction to BAM as this is shipped with jBPM5
Cheers