What applications enable AirPlay mirroring for Mac?

Do any applications enable AirPlay from my Mac to an Apple TV? I am looking to wirelessly mirror my Mac's display to the TV, similar to the way iPad 2 and iPhone 4S can mirror their displays over AirPlay.

Yes - it's coming as a feature for Mountain Lion, but solutions that work now on Lion are much appreciated.

Solution 1:

With the new OSX Mountain Lion you will be able to airplay from the Mac to an Apple TV.

http://www.apple.com/macosx/mountain-lion/features.html#airplay

Solution 2:

AirParrot is the application you are looking for. It does exactly what you want, mirror Mac screen to AppleTV. It works on Mac OS 10.6 and higher.

Solution 3:

You folks might be interested in knowing about AirVideo Server, and Airflick. The combination of these two tools will do what you want. It will use airplay to stream wirelessly from your device to atv2, doing conversion on the fly. airflick will send files from desktop to atv2. (And photo's, pdf's, desktop) Very cool stuff.