There are two things that Rendezvous got right: (1) They explained their technology in a compelling way to consumers -- here's what it can do for you. Conferences with wireless are changed with Rendezvous. (2) They explained their technology in a compelling way to hardware and software vendors so that we've seen shipping applications within the first six months of Rendezvous' public announcement.
Do Jini and Rendezvous have little in common? I would agree that Rendezvous doesn't solve the leasing and transaction and other problems that you detail above. But one of the biggest barriers to using Jini has been the "out of the box" problem. Getting it up and started.
I would argue that Jini and Rendezvous complement each other nicely. A Rendezvous enabled Jini application could lead to local dynamic grids built around JavaSpaces. Making the Jini lookup service a Rendezvous service could have interesting applications.