Yahoo's social networking effort called "Yahoo 360" did not enjoy the same rapid growth as industry leaders in the social networking space (enter MySpace and Facebook).
It looks like they are now attempting to approach this space with a slight twist. Take an existing service which has had success and tackle the problem from there. Also, rather than a breadth approach, they are going for depth.
The service I am referring to is Yahoo Answers. And Yahoo is adding a social network component to it. LinkedIn offers a similar service as Yahoo Answers. However, they approached it with a community/people first attitude whereas Yahoo Answers started from an existing service and is following it up with the networking aspects.