MediaNet is a completely redesigned free server software for the rio, exstreamer, slimp3 and mediamvp. it is fully modular which allows new features/devices to be added easier. it is under very active development and has support for the xPL home automation protocol and the ability to insert text-to-speech into the playing stream, allowing for caller id announcements, etc.
get it at http://www.myhap.org.uk
join the yahoo group at http://groups.yahoo.com/group/ukha_medianet
i'm not affiliated with the development, i'm just a happy user.