Contributed icons and layouts
layouts documentation
SongTree syntax for custom column or group

git repository : on github and sourceforge. See this mini-guide on using git to get the latest gmusicbrowser version in the wiki.
There is currently 2 git branches: master for the gtk3 version and v1.1.x for the gtk2 version.
IRC : #gmusicbrowser IRC channel on Freenode.

Future development versions will be announced on the mailing-list gmusicbrowser-announce (RSS feeds are available via gmane)

New gtk3 beta : gmusicbrowser- (released on 19-11-2020)

gtk3 beta for debian/ubuntu
Note that in v1.1.99.1 the icons play, previous and next and invisible unless you select an icon theme, sorry about that.

Probably outdated links:
repo for openSUSE 12.3(OBS page)
1.1.7 rpm for mandriva
1.1.7 rpm for fedora.
1.1.7 package for zenwalk
1.1.6 gentoo ebuild, ebuild for git master branch
1.1.8 package for arch linux
ochosi has set up this ubuntu ppa which tracks git master. Note that it contains some small changes from my branch, in particular the default layout and icons.