Update: Well that didn't take long. Here's what T-Mobile had to say in response.

We have seen the complaint filed today by the FTC and find it to be unfounded and without merit.  In fact T-Mobile stopped billing for these Premium SMS services last year and launched a proactive program to provide full refunds for any customer that feels that they were charged for something they did not want.  T-Mobile is fighting harder than any of the carriers to change the way the wireless industry operates and we are disappointed that the FTC has chosen to file this action against the most pro-consumer company in the industry rather than the real bad actors.