One of the reasons I like WordPress as a website platform is because it allows for easy social networking integration. Of course, you also need the social networking sites to easily integrate with your website as well. Jeremiah Owyang, of the Web strategist creates a useful maxtrix outlining which major social networking website provides what integration. He also lists where to go to set-up the connections.
When talking with lawyers, I make the point that linking out to your social networking profiles extends the reach of your website – for free.