Hi *,
as you did not had enough of me last week, here I go again: FOKUS recently launched the Open IMS Core.
Keeping it short: - project at http://www.openimscore.org (SVN, mail-lists, etc on berlios) - general information at http://www.fokus.fraunhofer.de/ims/OSIMS.php?lang=en or mailto:info@open-ims.org - you get P/I/S-CSCF, HSS, SIP2IMS Gateway, CDiameterPeer (as module for SER, also standalone usable), JavaDiameterPeer (100% Java and decent performance).
All in development, so if you look for stability, security or compatibility, you won't find it there yet.
-Dragos