Sing Li has a put together a series of articles on Java Management Extensions (JMX), "From Black Boxes to Enterprises" Part 1 and Part 2.  I consider Sing Li as being one of the best Java technical authors out there, I came to this conclusion after reading his JXTA series of articles.  Sing Li has also written books on JINI and JXTA, however I'm pleasantly surprised that he's now writing about JMX. I mean, Java manageability isn't as cool a topic as JINI or JXTA, but who knows, there might actually be something cool about Java manageability.

Speaking about JINI and Manageability in the same breath, a company named IntaMission, has released a free JINI admin tool.