Rogue Amoeba's Airfoil 3.1 is a major update to the audio streaming application that ushers in Apple TV and Windows support.

Airfoil users also enjoy overall improvements in the user experience, including: improvements to the Airfoil Speaker to offer skip-free audio; improved DVD support in Airfoil Video Player; improved performance on low-end machines; full compatibility with Front Row; and many other minor fixes and improvements.

Airfoil users can take audio from any application and send it to their AirPort Express units, Apple TVs, and other Macs and PCs running Airfoil Speakers.

The solution transmits audio from RealPlayer, Windows Media Player, QuickTime Player, and other media players. It also streams music from web-based applications such as Last.fm.

Airfoil Speakers is a separate application tht can be installed on any Mac or PC to turn that system into a virtual AirPort Express in order that users can transmit audio using Airfoil to a so-enabled machine.

Airfoil costs $25. Version 3.1 is a free upgrade for registered users.