The company first proposed these plans solely in Philadelphia earlier this year. They say that the trial was successful, AT & T on Tuesday announced its intention to expand the data plans for the rest of the U.S. this summer.

This means you’ll soon be able to buy mini ultraportable notebooks made by Dell, Lenovo and Acer at the discounted price when you get 3G data on one of AT & T in the retail store or on its website.

According to the IDC report published in April by the end of 2009, worldwide shipments of mini-notebooks could reach 22 million. It is obvious that AT & T wants its share of the growing Netbook pie.

Currently, detailed information on pricing and availability of new devices and data plans are not finalized, and AT & T stated that it was announced that at a later stage. Nevertheless, the company has made clear that with the built Netbooks AT & T 3G services will also be available through other national retailers.