I'm currently bashing my head against a wall. Both physically and metaphysically.
Nothing is cooler than Jini. However, unfortunately nothing is more obscure than Jini. It is something that exists etherally as a specification, not necessarily (although occasionally) as an implementation. It's the how, not the what. It's an adverb. Or something. My brain is lightly fried.
See, you can start with Jini's reference implementation via the starter kit, which exists as a concrete example of the specification. However, the last release was at the end of 2005. This is probably due to this implementation being picked up by the Apache Incubator and turned into Apache River. Apache River does seem to be under active development but has yet to issue an official release and has distributed just one release candidate.
Alright... so the Sun/Apache standard implementation is in transition. Who else has Jini services ready? Rio is a java.net project that appears to be both flexible as well as standards-compliant, so it appears to be a contender. There even appears to be moderate development traffic. However the stable binaries don't seem to match the current on-line documentation, and I haven't been able to download the latest milestone release. It does appear to have Spring integration however - and may yet be a contender. But until the documentation syncs up with the latest stable release, it's a bit hard to follow.
Cheiron also has an implementation with Seven that is Jini-compliant, and appears to be receiving some good development traffic as well. I'm still researching how to go about implementation, and their docs currently match up with their releases. I'm trying to (still) read their documentation and see what I need to do to get up to speed. It appears that most people discussing Jini in forums use Seven Suite as their implementation of choice, although Rio has a strong following as well due to its ease of Spring integration and nice administrative tools.
But for me this means I'm writing a helluva lot of "Hello World" and "Echo" applications, reading until my eyes bleed and trying to figure out how to get this all to work under a local development environment. Jini has been around forever... maybe I'm just having a hard time catching up with the rest of the world.
I'm hoping Spring Integration makes this all a bit more straight-forward for complete knobs like myself. Please oh please tell me they're adding Jini into the next milestone. Having ubiquitous services over a self-healing network is just too good. I'd love to be able to scale just by plugging in a server and walking away.