For a while now, I've been a vocal proponent of marketers participating in social marketing, and clearly many others see the potential as well. In his July 30 ClickZ column, Bill McCloskey shares some great data that illustrate the enthusiasm with which marketers have embraced social networking.

Since 2007, Bill's firm, Email Data Source, has been tracking how often brands embed a link within their email marketing messages back to their social networking site. The data point to two interesting facts: 1) the number of email marketing campaigns that contain links to the two top sites, Facebook and Twitter, have dramatically increased, and 2) in 2009, No. 2 Twitter began closing in on No. 1 Facebook, and in April surpassed its rival as the top social networking site for email marketers.

In 2007, Email Data Source tracked 215 emails with Twitter links and 729 with Facebook links. By June of 2009, the number of campaigns with a link to a sender's Twitter account soared to 41,399 and 41,052 for Facebook. You can view the stats here.

I do find it interesting that Twitter has surpassed Facebook. While Facebook's user base towers over Twitter's, Twitter is clearly the king of micro-blogging (at least today). A lot of the content that gets shared socially is the kind that lends itself to the quick shares that Twitter has made famous, but I have to believe that some of this traffic spike is due to Twitter still being in its “novelty” phase.