I've never known anyone that "had it before".... when tethering was first enabled, the only option to get it was to ditch your unlimited plan (which I've had since day 1). Believe me, I *tried*. Really wanted it. Did a quick google, and I can't find any mention of unlimited available at anytime with tethering.... must have been a trick to it!
Congrats on being able to do it, Wilson... you're the first I've seen! Well, unless you're jailbroken; that may be different. In any case, getting a bit off-topic here, so I'll let it go. One of these days I'll tether in my edge! :D