I have obviously been a bit out of the loop not noticing this before,
but anyway, the Steem Source was released under GPL on July 01, 2011.
It's got MIDI in it which is why this is interesting for us. There are
lots of editors for antique synths out there (or for their emulations)
as well as a bunch of funny auto-composers (M, Ludvig) and other
MIDI-toys. The original Steinberg Cubase Light is still freeware if you
need a 16-track sequencer.