Yahoo June 7 began integrating Facebook across more than 15 of its sites, adding a much-needed social component to keep its 600 million users engaged and returning to its content.
To this point, Yahoo offered a Facebook application on its homepage and basic share functionality throughout its media properties.
Beginning this week, users of Yahoo and Facebook will be able to link their accounts by entering their user names and passwords to share and view Facebook updates across both networks.
For example, those who connect their accounts will access their Facebook News Feed on the Yahoo homepage, in Yahoo Mail and other Yahoo sites and services.
Conversely, users who host content on Yahoo News, Yahoo Sports, Flickr, omg!, Yahoo TV, and Yahoo Movies will be able to share their actions with friends back on Facebook.
Yahoo offers screenshots of what these integrations look like on its corporate blog here.
There are no financial terms set for this five-year deal, which is Yahoo's attempt to get a social booster shot from the leading social network.
Yahoo pledged during its financial analyst event May 26 to focus heavily on delivering personalized content and applications to boost user engagement.
There is no better way to do that than by integrating with the world's leading social network; Facebook sports nearly 500 million users.
Yahoo isn't just leaning on Facebook for social capabilities. The company struck a deal with leading Facebook gaming app provider Zynga to put online games such as Farmville and Mafia Wars across its network of sites.
Yahoo also acquired Koprol, which enables Foursquare-like check-ins from mobile phones.
Yahoo June 7 also renamed its Yahoo Profiles identity and activity management dashboard Yahoo Pulse. The dashboard lets users manage what they share on Yahoo! from the external social accounts and apps that they have linked to Yahoo, such as Facebook.
What is clear is that Yahoo is either buying companies to inject social capabilities or outsourcing these capabilities to the likes of Facebook, Zynga and others.
Indeed, ReadWriteWeb referred to Yahoo as a social network aggregator, a sort of Plaxo or FriendFeed. Ironically, both of those startups were acquired by Comcast and Facebook, respectively.
GigaOM's take was more severe, noting that Yahoo's deal is a tacit admission that Facebook had won the social battle.
Both viewpoints are correct. The remaining question is whether or not Yahoo will not only retain what is clearly a legacy audience at this point, or tack on new users the way Facebook, Twitter and up-and-comers such as Foursquare do in the social Web.