Nuclear power plantDX Gaming has posted a nice article the compares the power consumption of today's and some of yesterday's consoles.

Just leaving the console on standby consumes quite a bit of power, with the xbox360 costing about $2.63 a year. Just displaying the 'dashboard' shouldn't be as processor intensive as running games, but the difference in power consumption between those states turns out to be surprisingly small. Both the Microsoft consoles can easily compare to a very bright lightbulb - 61W & 145W - when running the dashboard. Respectively 70W and 165W playing games.