On Limera1n’s official website, hacker geohot writes: “AppleTV is technically supported, but there’s no apps yet”. So yes, while you can jailbreak it, i.e. have administrator access, there really is no use for it for now.
TUAW writer Erica Sadunconfirms that she was able to get her Apple TV into DFU mode and was able to jailbreak it using Limera1n.
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