If you can come up with the right command line incantation to make this work I will sure be interested in seeing it. It sounds like it would be really useful, although if it became something in widespread use than I am sure the folks at T-Mobile and other commercial Wi-Fi networks will be less than pleased...

BTW, I did a little test on my own to confirm that Apple's built in Software Base Station capabilities in OS X 10.2.2 won't let me relay a connection to another Wi-Fi connected laptop here in my home office. When I tried to do this I connected one PowerBook to another using my Pismo as the relay, the two computers would connect but in the process it cut off my Pismo's connection to the wireless network here at home, defeating the whole purpose of the exercise...