AT&T representatives attended Mr. Allen's home town viewing parties and reports say that the reps offered free texting services to Mr. Allen's fans and gave out instructions on how to send multiple text messages at the same time. The rules of the show prohibit "power voting" using "technical enhancements". The carrier has said that the instructions on how to send blocks of text messages at one time came not from the company as a corporate service, but was the work of a "few local AT&T employees" in Arkansas. The company continued to say that these employees were caught up in the enthusiasm of trying to get a home town contestant to be named champion and as a result, they brought a small number of demo phones to parties which were offered to people to send texts selecting Kris Allen over Adam Lambert in the finals. The company said that they will make sure that their employees understand that such behavior is not to be repeated on American Idol or any other voting-type show. AT&T said that it "celebrates the competition, not individual contestants."
For it's part, Fox says it has a third party monitoring process that ensures the integrity of the voting. As such, the network claims that the actions of the rogue AT&T employees had no bearing on the outcome of the show and that the final results stand.
source: NY Times