Alright.. I had some time to debug what was going on today and figured it out. Seems like keeping perspective correction off solves the problem I was having. I have re-released the test-mesa.tgz code (see link in first post) and now GLU works too. It is set to render at 320x240 directly to the screen framebuffer. If you want 640x480 you have to change the WIDTH and HEIGHT defines in osdemo.c, and if you want to buffer the renders to then blit back an animation quicker, then you'll have to change the init code to render to a seperate SDL_Surface instead of directly to screen. It shouldn't be that hard.
Note that when you blit directly to the framebuffer it appears that the blue/red channels are switched. I'm going to fix this soon.
Software openGL rendering now works for the openXDK! (it _is_ really slow though)