Next up is a two-bit (not $.25) baseband hack that will re-enable sweet, sweet tethering on the most recent 3.1.2 iPhone OS-updated iPhones. The previous tethering hack only worked on iPhone 3.0 software and firmware.
Both of these are pretty hardcore, as they mess with your iPhone’s baseband. That definitely means that they fall into the "USE AT YOUR OWN RISK" category. As he and we remind you, this could also cause AT&T to do some extra gouging to your phone bill.
That being said, let us know if you’ve had any success in trying these or if there are easier ways to acomplish the above.