But they sell a 2GB and 4GB plans....so are they now saying that if you use your allotment, you abusing their system?
Nope. The throttling policy explicitly excludes any customers who have signed up for any of the tiered data plans.
http://www.att.com/gen/press-room?pid=20535&cdvn=news&newsarticleid=32318&mapcode=corporate
Customers who sign up for a tiered data plan can go above their tiered limit, and rather than getting throttled, instead they'll be required to pay overage fees. Personally, if the choice is between throttling or overage fees, I would prefer throttling, hands down.