As announced by Steve Jobs at the MWSF almost a month ago, it's finally available for the public! (Thanks to Jean-Jacques for the info).
This 2.0 update gives users the possibility to rent movies, buy music online (iTunes Store) and view both Flickr and .Mac slideshows, it also brings support for 5.1 HD sound.
The update is available through Apple TV.
[translation by xavier]