Is it possible to have a TCP/IP network using bluetooth?
If you're talking about using your mobile phone as a tethering device over Bluetooth then sure this is:

PdaNet




  Is Linux (Ubuntu etc.) supported?
  
  Meanwhile only Bluetooth DUN is
  supported (requires android 2.0) on
  Linux.
  
  We are working on a linux port for USB
  Tether but it may take a while.
  
  via junefabrics.com


EDIT

Sorry for misunderstanding you. Could any of the following MPD control applications on the Android Market help you?