I haven't found them yet, but after some more digging, not sure they'd be of much use. The older JS examples seem to rely on Jini 1.0-era lookup mechanisms and classes which no longer exist, AFAICT. Am currently cleaning up a local copy of the code from the JS Principles book to work with Jini 2.1.
Might be a useful TO-DO for a later River release to have some simple working JavaSpaces examples, tho. Patrick