Having seen a new social media news site and magazine being announced on G+, I think it will likely make a good case study in the power of social media. After being announced by a social media professional, many of her followers saw it and doubtlessly subscribed to is. They also shared it for all their followers to see, which is how I found out about it (thanks to +Robert Scoble ). I will be adding it to my RSS reader, and am also resharing it to my followers. I'm not as influential as the original sharers, and a lot of my followers aren't in the target demographic (an important point that many neglect!), but it still has the potential to be read by others.
Even after those echoes die down, there will be an ongoing effect. Most of the readers they got through social media, as well as many from other sources, will share articles they like or wish to discuss, and each "Like" or +1 could be the one that convinces someone else to check it out. If somebody even so much as comments on one of those articles, it will be reshared to all their friends. And it just keeps on spreading, and spreading, and spreading. And if they post it to multiple networks, the effect is even larger - especially since many people tend to interact with a different group of people on each social media account. Sounds easy, right? Unfortunately, it's not quite that simple for most of us.