Convergence among devices is one thing, but it's happening with accessories as well. The Duracell PowerFM ($79.99) from Battery-Biz is three iPod Nano (1G and 2G) add-ons in one: an FM transmitter, a protective silicone case, and a battery pack.
The transmitter sends your iPod's audio out to any FM radio receiver within about 8 feet via a user-selectable frequency, while the lithium-ion battery pack doubles the life of your iPod's built-in battery. The PowerFM isn't hideously obtrusive, and a pass-through port on the bottom lets you hook up other iPod accessories that use the iPod Nano's dock connector.