An RDF specification is available online. This specification is compatible with all versions of Gnomoradio >= 0.7 (in other words, both the Gnome 2 version as well as the Mozilla version).
A complete rewrite of Gnomoradio is rapidly being developed based on Mozilla. In addition to a large library of cross-platform network utilities, Mozilla enables scripted user interfaces written in XUL and Javascript. Currently, most work has focused on the back end. The new program can find and play local audio files in all formats that GStreamer supports. A Rainbow file-sharing client is in the works.
Build instructions can be found here.
Be sure to join the discussion on the gnomoradio-devel mailing list and to report any bugs on Gnome bugzilla.