As we discussed in some previous blog posts, Bing is making a bid to challenge Google’s dominance in the search world. We’ve already looked at Bing’s deal with Blackberry, which may give Bing a lot more traction in the mobile search market. Now we’re going to look at Bing’s deal with Facebook, which adds an exciting “social” aspect to Bing’s search results – and Google’s attempt to strike back.

Here’s how it works. Bing search results will now include “Likes” from Facebook. If you’re logged into Facebook when you make a search – say, to find a local plumber – you’ll get a list of plumbers’ websites, and if any of your Facebook Friends have “Liked” any of the websites in the list, you’ll see a little thumbs-up “Like” icon and the name of your friend(s) who “Like” the site.

Of course, when your Facebook Friends make searches in Bing, they in turn will be able to see which websites you have “Liked”. To make it as easy as possible for everyone to contribute their opinion, There’s even a Bing toolbar that lets you “Like” a website right from your browser controls – you don’t have to hunt on the website for the little “Like” icon.

It’s certainly handy to be able to see at a glance if one or more of your Friends “Likes” a website – especially when you’re trying to evaluate something you don’t know much about. Many people rely primarily on word-of-mouth to choose heating, plumbing, and electrical contractors, and “we think consumers searching for service businesses will quickly come to use “Likes” to choose one contractor over another.

But the Bing/Facebook integration goes deeper than that. Bing will actually use your Friends’ “Likes” to help calculate the search engine results it presents to you – that is, the sites that your Friends “Like” will get a higher spot in the listings. And because each person has a different group of Facebook Friends with different “Likes”, Bing will present a different set of search results to each person – a truly personalized search.

For businesses, this means that it will be increasingly important to encourage happy customers to register their satisfaction online. There are some great ways to do this, and we’ll revisit this topic again in future blog posts.