Yesterday, Verizon announced they will keep their unlimited data plan and offer a few options for casual users.
Even Sprint will have unlimited plans, as does Virgin right now.
AT&T can suck eggs. They don't deserve anybody's business. If you have no contract with AT&T, now is the time to tell them to shove it, go to Verizon, Sprint, or Virgin and get what you pay for, (and pay less in the process).