Barry,
I am surprised that you able to find that book, as O'Reilly EOL'ed the Jini book many years ago. I remember back when Scott and I were talking about updating it to the new release that just came out -- and learned of the book's demise.
As for where Jini is going, it seemed to have kinda slowed to a crawl. (Or maybe it is because I don't keep track too much anymore)
The last major commercial company that used it -- that I know about -- is a company called NextSet. This was a few years ago, and I heard that they may have been sold. They used Jini for a trading
exchange. Any vendor may join the exchange via Jini discovery mechanisms. (don't remember how they dealt with the WAN restriction though)
Hope this helps,
Henry