Social media, according to Wikipedia (where else?), consist of "the online tools and platforms that people use to share opinions, insights, experiences and perspectives with each other." This includes blogs, message boards, podcasts, wikis and vlogs. For a long time, they were considered related to, but separate from, mainstream media. That point of differentiation is now gone.
In 2006 all media became social. Pretty much every newspaper, TV network and publication (this one included) has wholeheartedly adopted these technologies. And the changes go deeper: Each is also communicating in a far more conversational tone -- one its audiences uses.
Meanwhile, the barrier to joining the media fabric has been obliterated by these very technologies. Lots of people are making nice advertiser-supported incomes either as solo or start-up media entrepreneurs. What's more, an entire new economy of service providers has propped up to help them do just that.
So as we roll into 2007, it's fair to say that "social media" as a separate entity is dead. Nevertheless, there are still two strata of media, both of which are now social. Big media bring lots of experience and resources but have become more of a two-way conversation. Indie sites, meanwhile, fill niches the mainstream media can't touch. They also have fewer church-state restrictions and operate at a lower run rate. It all fits together nicely.
The media today is like professional baseball. We have the minor leagues and the major leagues. Both of them include professional ballplayers. The big leaguers make more money and have more resources. But watch out: There are lots of hungry minor leaguers that may just be next year's all-stars.