AT&T is testing Internet broadband cap.

The days of all you can eat Internet broadband usage are closer to an end that you may realize. Slowly but surely, Internet service providers are rolling in Internet broadband usage caps. The latest in that string of companies putting in place cap limits, is AT&T who is following the footsteps of Comcast who has started a similar system at the beginning of last month in Texas. AT&T just confirmed that it is testing a new system for users in Reno Nevada. In that test, new users will be subject to two different caps depending on either they are using slow or high speed DSL service. Members of the first group will see their limit caped at 20GB of bandwidth per month while users of the fastest DSL service will see their limit set at 150GB per month.
Users in both groups who exceed their monthly limits will be billed $1 per gigabyte of data transfer following a one month grace period after their initial sign up.
In the meantime, all existing subscribers are not affected , but when they will as the company plans, they will all receive the 150GB limit. To help its subscribers monitor their bandwidth usage, AT&T is planning to provide them with a measuring tool; other third parties like Shaplus.com are already offering some types of measuring tools.
Anticipating no major setback, AT&T is planning to expand the new system to other markets soon.

For more see pcworld.com