I think the most significant addition is the new Anchored Help Chm Version %) The old one is not compatible with Windows Vista.
A really hard job to do, once I made this myself, you must go to each page and add anchors to each subtopic ;o) After, each keyword from index must be linked to the right page and anchor. (a optional thing is to make use of css and clean all html, mine look much more cleaner ;p)
Anyway it was fun to apply diferent technic to speed up that process %)
Now a updated Chm Anchored Help version at every release, it's good M$ decide to remove .hlp support ; )