peppy supports a client for controlling a Music Player Daemon server (also see the MPD wiki). This mode is being designed as an example of a non-file based mode, and as a urllib2 protocol that does not actually return a file-like object.
To connect to an MPD server, you can start peppy with a URL in the form of mpd://host[:port], for example:
python peppy.py mpd://your.mpd.server.com:6600
If a password is necessary, it will prompt you.
Or, you can use the Login menu item to login after a failed password attempt.
Here's a screenshot of version 0.6.4: