The Zaurus has an IrDa port build-in, but for security and power saving, it is disabled by default. You can temporarily enable it to receive files. Use the IR-Receive application under the Settings tab and enable it to receive files. You should disable it once you finished receiving files.
You can also send files via IrDa. For that, select the file you want to beam from the Files Tab and hold the stylus on it for a few seconds and select Send by beam....