It was actually Google Summer of Code student Egor Suvorov who implemented the Haiku MIDI support.
Thanks! :)
1.1 --- a/CHANGES Sun Jan 15 11:33:20 2012 -0500
1.2 +++ b/CHANGES Sun Jan 15 17:00:28 2012 -0500
1.3 @@ -27,7 +27,7 @@
1.4 * The music-finished hook can start a track immediately
1.5 James Le Cuirot - Mon Mar 21 16:54:11 PDT 2011
1.6 * Added support for FluidSynth
1.7 -Scott MC - Tue Jan 18 11:06:47 PST 2011
1.8 +Egor Suvorov - Tue Jan 18 11:06:47 PST 2011
1.9 * Added support for native MIDI on Haiku
1.10 Sam Lantinga - Tue Jan 11 01:29:19 2011 -0800
1.11 * Added Android.mk to build on the Android platform