Griffin Technology has announced that its iTrip Pocket FM transmitter is now shipping. The small device, designed to fit the bottom of the second-generation iPod nano, features a forward-backward frequency button, three buttons for user-defined preset stations, and a small plastic cover to protect the Dock Connector when not in use. It also makes use of SmartDisplay Technology to show frequency information directly on the screen of the iPod. The iTrip Pocket is compatible with fourth- and fifth-generation iPods and first-generation iPod nanos, and sells for $50. Learn more about the iTrip Pocket in our First Look article.