June 20 2007 Patch (aka the YouTube Patch)
As described in the Patch Over Network article, the AppleTV goes out to mesu.apple.com perodically and checks for updates, much like Software Update on "real" OS X works.
The DMG is accessible from http://mesu.apple.com/data/OS/061-2988.20070620.bHy75/2Z694-5248-45.dmg. It weighs in at 179MB (188,072,708 bytes)
Full file listing of the disk image
What has changed in the update from the original vanilla factory image?
I'm guessing a FRApplicance for the YouTube integration.
What is known about the update so far
- It breaks all Apple TV Plugins. All of the plugins will need to be recompiled with some changes.
-It will erase any modifications you've made to the Apple TV OS such as instlaling SSH, AFS, and special network mounts, however your Media partition will stay intact.
-All plugins will need to be tweaked and recompiled to work under the new firmware due to changes in the BackRow Classes.
-The firmware update seems to contain everything you would need to make your own patchstick legally without having to open up your Apple TV. It may also be possible to do a DNS Redirection for the update server url and point the Apple TV to your own customized filesystem updating the ATV over the network with an OS that has all of your plugins and settings pre-installed.
-The update includes some new code called: 'RUIDVDAppliance' This could mean a HD DVD / BlueRay addon for Apple TV is in the works?!?
-There appears to be support for pin-code protected parental controls