A few months ago, I published a small AppleScript that (through several great reader contributions) worked remarkably well at changing your iChat status based on your location, using the SSID of the connected wireless base stations as its cue.
Reaction to that story was great, and I want to thank everyone who participated or commented on it. Now I want to turn your attention to an alternate approach to solving the same problem: A script by Jon Bauman posted yesterday on Rob Griffiths' excellent Mac OS X Hints web site.
Jon's script is far more polished than mine, uses some different command-line commands, and seems to work. It's very customizable. If you're interested in your Mac reacting to changes in its location, be sure to check it out.