New networking code which isolates Internet i/o from the rest of the server internals.
The purpose is to cure the bug we see at rare intervals in which the server seems to "hang". It's actually not really hung, it's just trying to talk to someone whose network connection has disappeared in an awkward way. The new I/O architecture should make that, we think, impossible.
See today's MOTD for a link to the source of the new system we use. For programmers, very interesting stuff. Among other benefits, the server should be able to handle thousands of logged-in players. Do tell your friends.