Yesterday marked microblogging site Twitter's fifth birthday. As Brafton reported, the company had much to celebrate, boasting numerous landmarks – including brand awareness among 93 percent of U.S. consumers. A new eMarketer projection suggests that Twitter will also have reason to celebrate in the coming years, and marketers may consider the platform a mainstream channel they can use to engage their online audiences.

According to the firm's prediction, the microblogging site will steadily grow in 2011, reaching 20.6 million American adults this year – 26.3 percent growth over 2010. Adoption will continue over the next several years, with more than 27 million U.S. consumers expected to tweet by 2013.

EMarketers' forecast is favorable and strong, but these figures clearly position Twitter far behind Facebook in terms of social reach (supporting Brafton's earlier report that one firm found a Like is worth more than a Tweet). Nonetheless, the firm refers to Twitter users as a “vocal minority,” and they may help share content on the web and direct traffic to businesses' sites.

Plus, Brafton has reported that many social users are “creators” who link to content found via social media elsewhere on the web. With this in mind, brands should distribute content via Twitter (and other social outlets) to enhance SEO efforts – a strategy advocated by Google's Matt Cutts.