Recently we branched our stable source code and started to work on the redesign. In parallel to the redesign we are working on getting the client and server working on as many platforms as possible. The client is reported to work on Linux and Windows. At the moment there is a ready to use client for Windows and we are working on a compile manual for Linux. The source code is almost ready for MacOS, so it should be easy to port the client to MacOS. The server works on FreeBSD, Linux and Windows.
The stable branch can be found at the following URL: http://xmultiverse.svn.sourceforge.net/viewvc/xmultiverse/branches/stable/
Please join our IRC channel (#diversia @ irc.freenode.net) if you would like to help.