Besides using pyPortMidi to communicate to synthesizers and the like, it is possible to use pyPortMidi as a way to send MIDI messages between software packages on the same computer. For example, Using pyPortMidi and MIDI-YOKE on a Windows machine, it is possible to send realtime MIDI messages between programs on the same computer using loopback virtual MIDI ports.
This is a friendly fork of pyPortMidi from John Harrison which applies patches from the pygame fork. A Debian package has also been created.
See the downloads section to get the most recent Debian package or tarball.