Firmware

Unless otherwise stated, the jailbreak and unlock information report whether a device can be modified with publicly available software (read: no additional hardware required) if it was never jailbroken before. iTunes contacts ax.phobos.apple.com to check for updates.

Beware of scams that repackage freely available jailbreaks! Only use legit jailbreaks.

There has always been a big confusion about the firmware versions of the Apple TV (2nd generation), because the version numbers don't match the version number that is being displayed. Here's an overview. The best way to refer to a specific firmware is to use the build number.

Apple TV
The "Internal" version and build numbers refer to the "ProductVersion" and "ProductBuildVersion" keys in the IPSW's BuildManifest.plist.

The "Marketing" version and build numbers are what is reported on the Apple TV's About screen.