At only $99, the Peek was made to do one thing, and that was email. It offers no camera, no speaker, no FM radio, and is not even capable of making calls or web browsing.
A service plan costing around $20 per month will reportedly be available from T-Mobile, with no contract required. I think its inability to place voice calls will hinder its adoption as no one wants to carry around 2 or 3 separate devices.