As advertised on the web, the Apple TV comes with VoiceOver. Enabling VoiceOver on the Apple TV without sighted assistance is easy: Connect the device via HDMI to your TV or AV-Receiver. Make sure the appropriate port is choosen on your TV or AV-Receiver so that you can hear audio coming from it once its booted. Then connect the power to the Apple TV and wait for it to boot.
Once its finished it will announce to you that you are supposed to press the lower right button three times to enable VoiceOver.
Once thats done, the setup process is spoken as well. Once you choose a language, the VoiceOver language will automatically adapt.
If VoiceOver is enabled, it will speak all the on-screen menu items as you scroll through them.
You can rent movies from the Apple Store, browse internet movie sites like YouTube and Vimeo, listen to podcasts (very convenient) and a few other things I haven't had the time to personally test.
The on-screen keyboard that sometimes pops up for entering search terms or WLAN passwords also works flawlessly with VoiceOver.
One negative point might be that navigation is not always consistent, sometimes you use left/right to scroll a list of items, sometimes you need to use up/down.