José,
Hi Yoshiki, what are you doing with the midi support? are you using a plugin to reproduce midi or using the Squeak synthesis? If you've developed a midi plugin it would be also very useful for Scratch that lacks midi reproduction in linux..
Ian is looking at the VM primitives. For the October release, it seems that we are going to use ALSA sound driver and do synthesis in Squeak. In the future, some collaboration with other guys sound synthesis is on the horizon.
-- Yoshiki