On my search for improvements of GUI experience on Zaurus, I recently got interested in Sugar interface of OLPC:
http://wiki.laptop.org/go/Sugar. It's build around OpenHand matchbox we know from Angstrom, or pdaXrom. I would like to hear if anybody tried to play with it extensively. As far as the user interface is concerned, in the end what is good for kids should be good for adults as well ;-). And an intuitive and practical interface is what a small PDA/laptop like device definitely needs. Would it be difficult to compile it for Z?