I keep my music on a local Ubuntu server. Is there any way I can get iTunes to recognize the networked directory as part of its library?
you can try mt-daapd (firefly server) to serve media files to your iTunes from your ubuntu machine. Setup it on your server* and then add in Itunes Preferences->Advanced where your library is..
*this is a tutorial on how to install mt-daapd on your ubuntu server
Also bear in mind sometimes for some versions of itunes mt-daapd compatibility breaks. Updating to current itunes version usually helps...