Basically with this hack you will install a carrier update or profile and you will be able to enjoy tethering. In your face Apple / AT&T (not my case, but i know most of you will say that ) .
iphone os 3.0 tethering
Posted inHOWTO
HowTo: Enable Tethering in iPhone OS 3.0 Using MobileSafari ( AT&T )
Instructions on how to enable tethering for users on the AT&T and other networks using MobileSafari.