Google is adding a new feature to its search engine that lets you upvote search results. The feature has been named +1 (plus one), which, as you probably know, is commonly used on forums and similar discussion mediums to indicate that a person agrees with a previous post.

Sites that appear in search results will now have a +1 button next to them, allowing you to recommend a specific page or advertisement. Google displays the sites that you and your contacts have +1'd so you can instantly see who recommends what and make your decision accordingly.

"The beauty of +1's is their relevance – you get the right recommendations (because they come from people who matter to you), at the right time (when you are actually looking for information about that topic) and in the right format (your search results)," the company explained.

"Say, for example, you're planning a winter trip to Tahoe, Calif. When you do a search, you may now see a +1 from your slalom-skiing aunt next to the result for a lodge in the area. Or if you're looking for a new pasta recipe, we'll show you +1's from your culinary genius college roommate."

The service could eventually include other networks like Twitter and it might show how many people across the Internet have +1'd a specific result. Google also hopes websites will add a button to their pages so you can +1 things from around the Web – similar to Facebook's "Like" button.

The feature is being rolled out slowly and English-speaking users should be able to opt-in through the company's experimental search site. It remains to be seen how successful +1 will be, especially given Google's recent failures in the social domain (namely Google Wave and Buzz).

Unsurprisingly, new feature is already facing criticism. "Why would I '+1' a link to a page before I've seen whether I like it and why would I go back to the results if I've found the best result?" asks Alex Rainert of Foursquare. Do you have any initial thoughts on +1? Will you opt in?