Appearing atop Google's search results used to be the exclusive right of Web celebrities and Fortune 500 companies. Starting this week, your mom is just as likely to show up at the top of those results—providing she uses Google's still fledgling social network, Google+.

The change represents a fundamental shift, as Google's algorithm-driven search is going through a social overhaul as it attempts to head off the threat of disruption from socially focused companies, such as Facebook and LinkedIn. The new Google service, called "Search, plus Your World," is part of that effort.

Over the next few days, Google will start adding information that has been shared publicly and privately on Google+ to its search results.

This means you might see a picture of a friend's dog when searching for Pomeranians, or a restaurant recommended by a friend when you search for nearby eateries. Even if you aren't a Google+ user, Google search results will show content posted publicly on the social network that it judges to be relevant—profile pages and pages dedicated to particular topics.

The goal, says Google fellow Ben Smith, is to deliver more personally relevant results. "We're interested in making Google search as good as we can," says Smith. "But we need to know who your friends are and what your connections are. Google+ provides a great way of managing your connections and your friends and lets you make your search results better."

The only problem is, until more people start using Google+, these search results will include just a small fraction of the social information available online. The rest exists in unsearchable silos owned by Facebook, LinkedIn, and other smaller social media companies. Facebook presents a particular problem for Google because the vast amounts of personal information that its users post can be turned into powerful ways of filtering information and finding recommendations (see "Social Indexing" for more on this effort).

"Over the past several years, people have been benefiting from a growing diversity in the channels they use to receive information," says Jon Kleinberg, a professor at Cornell University who researches the way information spreads online. "During this time, a major axis along which our information channels have developed is the social one." 

In June 2011, Google launched a way for users to recommend web pages by hitting a "+1" button next to a search result. These buttons can also be added to Web pages, where recommendations will feed back into search results. The approach is similar to Facebook's "Like" button.