AT&T has officially delivered on the threats made by its consumer business director Ralph de la Vega last December: it’s switching to usage-based pricing on data plans for smartphones and the iPad. Starting Monday, all new AT&T customers who buy an iPad, iPhone, Blackberry or other smartphone and purchase the necessary data plan will have two options: $25 for 2 gigabytes, or $15 for 200 megabytes.

If you go over the 2 GB limit, you’ll have to pay an extra $10/GB. If you go over the 200 MB limit, you’ll have to cough up $15 for another 200 MB.

According to the Associated Press, current users will keep their $30/month unlimited plan, even if they renew their contracts. Update: The same goes for existing iPad owners who buy/activate a 3G-enabled iPad before next Monday.

Although capped data plans suck for consumers, it’s worth noting that if you’re not a heavy data consumer, it’s theoretically possible to end up paying less per month for a new iPhone starting next week. Just don’t expect to watch a lot of movies or YouTube clips, or transfer files via a third party document manager, or install a lot of apps when you’re on AT&T’s 3G network. Really, if you just remember that 3G is more of a subscription-based idea than a service, you’ll do fine.

“AT&T caps iPhone data usage with new wireless plans” [San Jose Mercury News]

Want more consumer news? Visit our parent organization, Consumer Reports, for the latest on scams, recalls, and other consumer issues.