Using the arm.ipk file from Dennis Wagelaar I added the aprsd daemon to the Zaurus.  This build of APRSd runs on the native Linux of the Zaurus and is compiled for the default Sharp ROM.  It is fairly easy to install and configure and runs from a standard terminal window.  Dennis has also compiled the soundmodem utility which could be used with the SL-5500 which has audio input.  The SL-6000 does not have audio jacks so it must be run using a TNC from the serial port.  Here is a screenshot of APRSd running on my SL-6000:

zaurus APRSd