As we approach the new year, millennials are one year closer to coming of age and growing into the nation’s leading generation of shoppers. A new report from L2 – a self described “think tank for digital innovation” – reveals that this demographic is influenced by social media branding, and it can’t get enough of news online.

The study found that Facebook is the leading source of Gen Y media consumption. Eighty-one percent of millennials use Facebook each day. This could be good news for brands with a social presence, as 75 percent of these social users have affinities for brands and 12 percent call themselves “devotees.”

The study found that branded email newsletters are the most powerful interaction tool, but Facebook is fast-becoming the digital version of word of mouth. Thirty-eight percent of respondendts frequently leave comments on brands, more than half (54 percent) have Liked a brand in the past month and 30 percent have shared brand information via Facebook to other networks.

When explaining why they engage brands on social media, Gen Y-ers primarily say they are looking for promotions or coupons (which marketers may take as a sign that Groupon will become a more important social channel in the next year). At the same time, 15 percent of female Gen Y-ers and one in 10 male millennials say they follow brands because they like the content the companies provide on social channels.

For marketers, this indicates that social media spend should keep up with millennials who are active on the space. It also signifies the importance of seeding social sites with original, custom content. The survey shows that each month, Facebook users share 30 billion pieces of content – including web links, blog posts and news articles.

This data supports Brafton’s report that marketers should prioritize investing in social content marketing in 2011. Using social sites to deliver branded, custom news marketing content may help brands get an edge, as the sruvey shows online news consumption is a rising activity for Gen Y-ers, and Brafton has reported that nearly one-third of consumers favor brands affiliated with news content.