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.

In April 2011, Google launched Google+ as a direct competitor to Facebook. The site won compliments for some of its features, like the ability to put contacts into different “circles” so that information is shared in a more controlled way. But, after rapid early uptake, Google has struggled to capture market share from Facebook, and has around 60 million active users, compared to Facebook’s more than 800 million.

The new features may not only make Google search more useful, but also encourage greater use of Google+. Showing Google+ profile pages and topic pages prominently could encourage people to create their own profile and topic pages.

The new service pulls in social information only from Google+ to start with, but, Smith says, it could include other, non-Google sources in the future.

Google is working hard to make its most popular services more social. Whereas an algorithmic approach to finding and sorting online information was once a source of nerdy pride for the company because of its objectivity, Google is fast reinventing itself as a business that values the suggestions of its users and their friends.

How people will come to use social signals to find useful information isn’t yet clear, though. “The most natural mode of use is still fairly up in the air, and it will be fascinating to see how people’s online behavior evolves in this dimension over the next few years,” Kleinberg says.