shows you how to get free tethering on an iPhone 3G, or 3Gs without a jailbreak! People have been saying that this does not work for a regular iPhone 1st Gen, but you can test it yourself.
Install and Use Tethering on iPhone 3GS or 3G.
Tethering: Be able to use the 3G Signal on a computer Mac or PC.
tutorial for connecting any iPhone to a computer wirelessly and sharing its internet connection with that computer. Works on the iPhone 3G, 3GS and 4. No jailbreak needed.