MSNP16
MSNP16 is used in a pre-release version of Windows Live Messenger 9.0, leaked in December 2007. aMSN also supports MSNP16.
It features "Multiple Points of Presence" (MPOP), the ability to sign in at 2 places at the same time with having chats replicated at all places. The UUX data have been extended to contain Endpoint Data (also MPOP), as well as Signature Sound MSN Object Data.