Google (in the UK only) has slipped into a little black number today.

There was a lot of coverage when the search page Blackle was set up, allegedly saving power by leaving pixels ‘unlit’ in black instead of Google's usual white, but it turned out that most modern computer displays use the same amount of power no matter what colour the background is.

So instead, Google are doing this to raise awareness of Earth Hour, which is taking place this evening at 8pm GMT. You can read more about it on this page from Google.