musicd (music daemon) is a music indexing and streaming server for Posix systems (such as Linux, *BSD and to some degree, Mac).
There has been no official releases for almost a year, and that will hopefully change soon. All the changes will probably get a Changelog once 0.3.0 is released.
There has been some development towards an HTTP API and browser client using it. Currently there is something available on the GitHub repo, and a full hacky implementation is available (that tar might change without prior warning). celeron55 explained about that in his blog post, and some real reference documentation will be done at some point.
Now that there is actually more than one people working on musicd, we have an IRC channel: #musicd @ Freenode. Come and have a chat!
These releases include support for on-demand transcoding and much faster scanning. Musicd also now scans album images - there is just no way to see them with clients yet (hack available, apply patches with git apply). See downloads.
First release of both musicd and QMDC. Both applications are now finally mature and usable enough for everyday usage. See downloads.
A freeform list of current features:
MusicD alone is not useful - it can't be controlled or play music by itself. For that a client is necessary.
qmdc (qt musicd client), implemented in Python 2 with PyQt4 and a custom C module for audio decoding and output, is currently the "reference client" and is developed alongside musicd.
IRC channel: #musicd @ Freenode