Knol Books idea is now actively being pursued. The number of books available is more than 50 now. There are gaps in these books. But the authors may recognize the gaps now more quickly and fill the gaps. Among knol authors also, knol books transfer information very quickly about gaps and availability of articles on various topics of subject.
The books can be accessed through:
Knol Book Catalogue
List of Knol Books by KVSSNRao