Could Google's Achilles heel be showing as Facebook teams up with Microsoft? "Microsoft advanced its partnership with Facebook this week, a move that could represent the biggest threat to Google's search standing yet. Microsoft and Facebook announced that they're teaming up to make Internet searching more social. Now when someone uses Microsoft's Bing search engine to look for a new car or a book, she can see which ones her Facebook friends liked. It will now be easier for searchers to get their friends' opinions before they make purchasing decisions. Industry watchers said this was an interesting development for search in general, but it also holds big implications for Google in particular. What's notable is that Facebook turned to Microsoft for this deal and not to the search market leader, Google."