APRS - Automatic Postion Reporting System, is the latest application for packet radio, created by Bob Bruninga, WB4APR.
I am on-air as of December,2004 using a TinyTrak 3 from byonics.com, easy to build and put on air.
Haven't run APRS since 2005, but now back on-air 23 May 2009
June 2009 - ran up Xastir APRS client on Xubuntu 8.10 and Debian 5.0 both work well.
Now running Xastir node on Ubuntu 9.04 and a UIView32 node on W2K3.
Australia (VK) APRS frequency: 145.175 Mhz (right on the input of a ZL voice rptr input - that was clever)
New Zealand (ZL) APRS frequency: 144.575 Mhz