For new iPad customers, the $25 per month 2 GB plan will replace the existing $29.99 unlimited plan. iPad customers will continue to pre-pay for their wireless data plan and no contract is required. Existing iPad customers who have the $29.99 per month unlimited plan can keep that plan or switch to the new $25 per month plan with 2 GB of data.
http://www.att.com/gen/press-room?pid=4800&cdvn=news&newsarticleid=30854
as long as you keep the autorenew up you can keep the unlimited. Pretty pissed about this, the unlimited plan any time I need it was why I spent the extra 130 bucks.