Back in May the District Court of Washington ruled that AT&T could not legally preclude their customers from filing class action suits against them. For a full recap of the whole mess, you can read the article linked above.
To sum things up, AT&T tried to stick a clause in their contracts that forbade their customers from bringing them to court in anything but an individual basis. The district court said that was ridiculous, the class action suit proceeded, and the evil behemoth megacorporation was defeated for the day. Now, three months later, AT&T is trying the same damn thing again.
Boy Genius gives a good brief of the situation. ATT's added another caveat to its terms and conditions. This clause tells customers that they will not be able to bring class action suits against their carrier. Only binding arbitration or small claims court cases are listed as allowed. As AT&T put it,
“Any arbitration under this Agreement will take place on an individual basis; class arbitrations and class actions are not permitted.”