One of the more interesting features to me was the "document zippers" that lets you programmatically navigate the doc as you might a tree structure in many functional languages.
In addition, the output is certainly more convincing at this time.
Hmm. Patoline sounds cool, but in that book, I have a lot of trouble distinguishing text from code. They don't put a box or even whitespace around code blocks.
http://patoline.org/patobook.pdf