Griffin Technologies Releases iTrip Universal
"Use with any audio source that uses a 1/8"(3.5mm) headphone jack-iPod, Sansa, Zune, portable CD players, you name it. Recharge iTrip universal's internal battery in any USB port (no more replacing batteries!), then connect to your player with the included stereo audio cable. Three user-programmable presets save the best frequencies so you can access them quickly later. User selectable stereo/mono output. Wherever you go, iTrip Universal is the perfect partner for your portable audio."
If you want to broadcast the audio from your MP3 player, phone, or anything with with a 3.5mm headphone jack to a nearby FM radio, this looks like a great solution. The battery in the iTrip Universal is only 180 mAh though, so I take their statement of being able to broadcast for "hours" to mean "more than one hour". It's a bit surprising they don't have an actual rating for the battery life.