Wireless music sharing isn't a new concept--just take a look at the Microsoft Zune, which lets you beam songs to other Zune owners with the press of a button. The problem with the Zune is that everyone you want to share with must have that specific brand of MP3 player.
Aerielle is offering a different take on music sharing with the i2i Stream, a device that connects to any MP3 player and headphones. Each i2i Stream acts as a transmitter and receiver, allowing the user to either broadcast music or tune in to others' "stations"--and either one is extremely easy to do. No doubt, the concept isn't for everyone, but for those who like to rock out in groups, it's a great solution.
Aerielle sells a pair of i2i Streams for $99.95, so you'll always know someone who has one, but the price needs to come down quite a bit before we'll consider it a value. .