I just converted my 2GB plan to unlimited as per the 2G iPhone trick. I'm worried I'm going to hit about 5GB this month at the rate I'm going. Has AT&T ever intervened or canceled anyone for using too much data? 
I just jailbroke my phone and using the MyWi app and I'm just burning through data with tethering.

I just jailbroke my phone and using the MyWi app and I'm just burning through data with tethering.