On my plan, not only do I have to pay for tethering on my "unlimited" plan, I am also limited to 3 or 5 gig of tethered data depending on how much I pay for tethering! The data on the phone is unlimited, tethered data is not.

That's a hell of a rent-seek for "-j MASQUERADE" at the bottom of it all. Sigh. jailbreak. This sure is going to seem quaint to our kids.