Using your 360 as a U-verse receiver comes with some limitations. For starters, it only works as an additional receiver. You'll still need a dedicated primary U-verse receiver. The service also only works with hard drive equipped Xbox 360's. The "kit" to enable U-verse on your 360 will run new subscribers $99, which includes having a technician install the software. Engadget speculates that existing customers will have to buy the kit and pay another $55 for its installation but the press release does not provide details.
Here's how the press release describes what you get with your 360 as a U-Verse receiver:
Using your Xbox 360 as a U-verse receiver, you can receive chat and game invitations from friends through Xbox Live while watching live TV and switch seamlessly from game to TV mode without switching video inputs on your TV screen. You will enjoy virtually the same U-verse TV experience and features available today, including the ability to watch live TV, manage and play back DVR recordings and access interactive apps, your program guide, the On Demand library and more. U-verse TV on Xbox 360 also allows customers to avoid an extra box on their entertainment center and the need to pay a monthly rental fee for an additional receiver.