To update [[http://gajim.org|gajim's]] status with your currently playing song, open [[http://gmusicbrowser.org|gmusicbrowser's]] settings, navigate to the plugins tab, and make sure now playing is enabled.

As command, enter

''gajim-remote change_status online %a-%t''

Or whatever you want to submit. Note, if you want to use spaces between artist and title for example, you'll have to use single quotes, like this:

''gajim-remote change_status online '%a - %t'''

For the development version of [[http://gmusicbrowser.org|gmusicbrowser]], there's also an option to run a command when music stops. 
You'd want to enter something like this there:

''gajim-remote change_status online ''