This doesn't add anything to the conversation, but two of
my odds-on favorites are BEA's Tuxedo and NCSA's Habanero.
Tuxedo is a high performance distributed transaction support
system that allows you to define abstractions (which they call
domains) for determining how and when messages are sent and
what type of priority you can assign to each.
French, and very corporate.
Habanero is a framework of collaborative tools whose main
contribution is to take care of some of the messaging and
fine-grained notification services for people collaborating
on an activity. You can compose their 'services' into
larger applications. They also have a good page on
the lore of red hot chili peppers.  Grad-schoolish,
and very research.