T-Mobile U.S. has released a streaming TV app called T-Mobile TV, which streams a selection of television programs to your phone. You don't have to be on T-Mobile to use it, but you do have to be in the US to get it. T-Mobile TV includes both live TV from select content providers as well as previous episodes. You can mark certain programs and episodes as favorites for quick access. For the first thirty days, users can stream a small selection of content from the app.
There are several content packages that you can purchase, the cheapest starting at $5.99 per month for smaller, specialized packages, and going to $12.99 per month for the largest one. You can, of course, purchase multiple months at a time. This app is not unlike those from different cable providers like Time Warner Cable and Comcast, though you pay to access the content through the app, rather than getting free with a cable subscription.
The app itself is free, iPhone-only, and available on the App Store right now. If you try it out, let me know what you think. How's the selection and performance for you?