The Web 2.0 Expo in San Francisco kicked off on Tuesday with the "Media's New Business Model" panel, moderated by WSJ's Jessica Vascellaro. On it, panelists noted that news sites are seeing site referrals from social media services like Facebook and Twitter grow at a much greater clip than from Google.

The Hearst company, for instance, says traffic from social media sites is increasing 250% faster than Google's search results, according to data from Heidi Perry of Share This, a company that provides content sharing technology for publishers and other content providers.

Google remains by far the top traffic generator though, but sites need to do a better job of retaining that traffic. Tristan Harris from Web engagement firm Apture says while 30% of news sites' traffic comes from Google, 30% of that traffic goes right back to Google. (ie: they see the headline on Google, click the link to read the story, then return to Google for more headlines).

Meanwhile, traffic gained from social media services tends to be more sticky. That's a benefit of adding Facebook "Like" buttons or the new ability to embed Twitter feeds into sites. They integrate the functionality of the social networking service into the site itself so there's no need to constantly go back and forth between search and service.

Given Google's ability to stream music from search results, this is something participating streaming providers should keep in mind.