Jason Lenhart

I recently completed reading JavaSpaces Principles, Patterns, and Practice and found it to be a quality book on the subject.  This was a great introduction to the concepts and implementation of Space Based Architectures. 

Coupled with the introduction are plenty of great examples, applicable to the Web 2.0 architecture being evangelized these days.

One thing that was really neat about this book was the foreword by David Gelernter, the father of Space Based Architectures.