Notice it doesn't go the other way though - the 5W adapter is not listed as compatible with the iPad, even though it can still charge it, albeit at a slower rate. Thanks for the correction on 12W adapter though.
The same goes for MacBooks.. i can charge my air using an 85w MBP supply if i wanted to..
I'm still trying to re-iterate the point of AC cables vs. DC adapters.
an AC cable is rated based the AC in your country. so yes, they do have ratings.. if i tried to plug my bluray player into an AC outlet in england, i would fry it..
but if the AC cable was designed for use in the US, its made for 110-120v.. so for the most part, trying not to get to technical, i could use the same cable on any of my home consumer electronics and it would work just fine.
now, yes, we can get to semantics and say, if i have a high wattage amplifier that draws 6amps, then, maybe i should stick with the 10amp rated power cable that came with that, and not use the 2.5amp one that came with my Apple TV..
and in the same way as using a larger power adapter on an iPhone, if i just went out and bought a 15amp rated power cable, then i could use it for anything in my house and never worry about it..
yes, there are "ratings" on everything, but the original point i was making was that macrumors was saying the Apple TV comes with a power adapter, when, in fact, it does not.