Birds' Nest on Live.com
However Microsoft China decided to go one better and have a full page backdrop of the Birds' Nest stadium on their page (see http://www.live.com/?mkt=en-cn). Very nice.
It's amazing the number of people who have seen the Olympics pictures on my screen and asked "how do I get that?". It's one of those simple little things that's a great idea - credit to the search team.