As luck would have it, our frame relay provider had a Problem last night, coincident with a scheduled power shutdown in the suite where our server and network racks live. So when the systems came back, "the intarweb" didn't. We spent all morning in a mild panic trying to figure out what was misconfigured. Corporate IT was out to lunch (it was noon in MA,) and our pal over there who is our go-to guy was on a flight to Portland, so nobody was answering calls. I was doing a lot of troubleshooting with my iBook, and I found it cumbersome to manually manipulate its routing tables every time I went back and forth between our wired networks and the wireless.
I like that my iBook Just Works™ wherever I go. I plug it into my house network, and it works there. At work, same deal. 802.11 at the mall or the airport, booyah. I never have to open the Network control panel, or issue shell config commands. But I would like it to add the static route to the DMZ when it comes up on the work network. I can reasonably recognize the work network by combination of what range the DHCP-provided IP falls in, and the default gateway router.
This hint talks about a script in OS X that gets called on network changes. It applies to an older version of the OS, but under 10.4, the script you patch is
/System/Library/SystemConfiguration/Kick. I'm going to mess with this a few days, and see if I can get it to tweak proxies and default printers for me too. (I can't tell you how often I'll go to work, print something from my iBook, and then I don't see it 'till I get home because it patiently waits to see my home LaserJet.) I'll post the results here...