While surfing around a bit, I came across this page. This page contains a simple USB-MIDI driver for Linux.
What's interesting about this is that there's already a "Makefile.zaurus" in the TAR -- in other words, it seems like the author wrote it so Zaurus support could be enabled provided there's a USB-host. (Maybe. )
What I'd like is to try it out at least with my MIDISport. Someone just needs to make a nice ipk (or at least a compile) for people like me who don't have full Linux machines with all the ARM support ready.
If this works, maybe I can play around with MIDI in Python or something. (I am not aware of any Qt MIDI software.)