You may want to check on Chandler, from the OSAF foundation. Their website
mentions everything, so I'll just refer you there:
http://chandler.osafoundation.org/
Of course it's still in an early stage of it's development, but it's
foundations
(semantic web and other research stuff that interest at least me) are very
promising.
Early stage since 4 years... so I won't hold my breath for that (but
still hope they will deliver one day)