In addition, what if this actually interferes with an emergency call?
Data and voice operate independently of one another. While 3G/EDGE service may be disrupted it won't affect end-users' abilities to make calls over GPRS. And while it may further reinforce AT&T's point that their end-users gobble "too much" bandwidth, the publicity that it could generate would be a nice way of sticking it to yet another corporation that enjoys selling "limited-unlimited".
There is plenty of examples...
Really? I know this is
Don't tell me how hard you work. Tell me how much you get done. -- James J. Ling