In addition, Yahoo decided to open up its MyWeb 2.0 application programming interfaces (APIs), which will allow the wider programming community to create other uses for its new search engine.

Walther says that Yahoo is also soliciting comments from Stanford engineers on the project, and will also approach research labs across the country for input and design ideas.

It's too early to tell if either Yahoo's or Google's new service will upend the balance of the search battle. Yahoo has already taken up Google's strategy of releasing beta versions of products to gauge the public's reaction. Still, it's striking that Yahoo is tinkering so dramatically with its core product.

"Yahoo is getting back to the roots of the company," says Walther, responding to a comment that the company's penchant for releasing beta products wasn't as strong until Google started doing it. "It's the way we used to do it. The company was founded by two engineering students -- and this is all about engineering."

Yahoo hasn't laid out plans about how it will monetize this new development, but there are several possibilities. On one hand, it's another advertising strategy, since it generates search results around which keyword ads could be placed. On another level, "it can build search loyalty," says Charlene Li, an analyst with Forrester Research.

Li says that people using social search methods with friends and others in their network will be less likely to go elsewhere, and therefore might potentially also purchase items from Yahoo Shops or sign up for a premium Yahoo email account. 

With MyWeb 2.0, it's clear that Yahoo is looking to differentiate and reposition itself as a leader in Web searching --  a title now held by Google. Its new approach is unique among the search giants, and it taps into growing user acceptance of the concept of tagging.

"Yahoo is trying to find new relevance," says Greg Sterling, an analyst with The Kelsey Group. "MyWeb 2.0 adds the community layer and brings in...people capturing content, something Google doesn't have."

Eric Hellweg is an award-winning writer and editor who has covered business and technology for over 10 years.