Enterprise Social Messaging Experiment
I must be asleep at the wheel. How did I miss this one?
From the Apache ESME (incubating) project's status page: Enterprise Social Messaging Experiment (ESME) is a secure and highly scalable microsharing and micromessaging platform that allows people to discover and meet one another and get controlled access to other sources of information, all in a business process context.
Wow, that sounds cool and it just landed in the Apache incubator. I need to learn more. There's no code in SVN yet, but there is a blog and a Google Group that I've yet to explore.