If you want to do a search for something online, you google it. You don't bing it. That just sounds bad (and perhaps inappropriate). Google has been the search engine giant for over the past decade. Other search engines have been trying to play catch up, and some have done relatively well. Microsoft announced bing.com not too long ago, and it has been doing quite well. Not well enough though for bing to succeed without piggybacking off Google.
Google had been suspecting bing of copying their search engine results, so they set up a trap to see whether or not they were right. They were.
Interesting. I think I will keep using Google.