Apple has announced that Mountain Lion will support Mirroring via AirPlay to an AppleTV, but it will require that it be a 2011 Macintosh. (See specs.)
Meanwhile, AirParrot 1.3.2 already supports Snow Leopard (10.6.8) or newer on Mac and XP or newer on Windows. Like Mountain Lion, it requires AppleTV 2 or 3.
It does provide 1080p video mirroring, will mirror specific applications without the rest of the desktop cluttering the screen (OS X only), uses Desktop Extension (OS X only) and mirrors the computer desktop to AppleTV.
I have used it to stream the beta Hulu Desktop app to my 2nd Gen AppleTV, but even there, Hulu does stop selected video from streaming. But in general it has worked flawlessly.
- Single User License $9.99
- 5 Seat License $29.99
- Demo version available for download
They do accept Visa, Mastercard, Discover and Amex as well as PayPal for Payment. They will provide quotes for 20+ licenses.
See it all for your self at: http://airparrot.com/