There is a 3rd party company supposedly developing a WiFi MS.
Currently the only option available for the older Cliés is the PEGA-MSB1 Bluetooth Memory Stick. This does make your Clié wireless, but Bluetooth is not compatible with 802.11b WiFi.
You can, however, get an inexpensive Bluetooth USB "dongle" for your computer, and use ICS to link your Clié to email & internet. Range is only about 10 meters (33 feet), but it works well with a good browser like Xiino.
I use this set up at work to take notes and IM or email them to the appropriate people. It's simpler and faster than scribbling a bunch of notes on scratch paper, then trying to remember to type it all up in a computer and send it later.
Health is merely the slowest possible rate at which one can die.