Apple AirPlay sounds great, but the number of devices that are actually supporting it are limited. AirPlay allows the iTunes fans to stream their music all around the house without needing wires. AirPlay tech is integrated into all sorts of accessories from speaker docks to AV receivers for the home theater.
The idea is that you can start your playlists on your computer and then stream them wherever you want. One of the cooler features of AirPlay is that if you have multiple Airplay compatible devices in your home you can listen to the same music on all of the devices at the same time.
AirPlay will also stream information about the music to your devices as well. You can get the album artwork, name, artists and more.