Take a look at this diagram:

North American marketers see major improvements when integrating email marketing and social media efforts. This is another proof that the power of digital marketing lies in channel integration, and not in short term campaigns. As social web marketing requires an ongoing nurturing of branded online assets (brand’s Facebook page, Twitter account, on so on), the biggest advantages are for those who combine different channels to utilize these assets.
This information also sheds light on the expected announcement of Facebook Mail today. My friend Yaniv Golan have some interesting thoughts about this move.

In a world were marketing ROI becomes critical for brands success, the combination of strong branding tools with direct marketing tools provide major advantages to the ones who use them well.