Much was made over the use of the BringBackOurGirls hashtag including the tweet from Mrs. Obama. Reasonable is the belief that the use of the hashtag could build unity between people who cared about the issue. Unreasonable was the belief that anything substantial would happen because people were using the hashtag. This unreasonableness was demonstrated by the mocking of the hashtag by the terrorists who stole the girls.
Diving into something which is more of the conspiracy theory type of consideration is how this type of effort could be used for other issues. For instance, frequently there are twitter bombs used by various organizations, spanning the political realm, to generate focus on a particular issue. As many people are driven by the social aspect of social media, this deluge of tweets can have an effect on this sect of the population.
In an unrelated topic (for now), consider that a high percentage of the population consider voting to be useless. This feeling is substantiated either by the belief that all politicians do roughly the same thing or that their issues never succeed in the political realm. One can argue that political parties attempt to reduce the desire to vote in those whom are not predisposed to vote their way and therefore have been the primary driver of this type of cynicism.
Another unrelated topic (yup, for now) is that politics is driven to a certain point by the polls and popularity. Not all issues are driven by this facet but those which are pursued without popular support can reek havoc upon the party driving those issues. A sidebar is that sometimes popular opinion can be driven by convincing enough people that an unpopular opinion really is the popular opinion and thus get that exact result.
Now, back to the twitter world. Popular theory is that most of the active twitter world are political activists. Also, recently it has come to light that more than half of the followers of President and Mrs. Obama are fake. These fake accounts are owned by someone and are active. Having large numbers of followers is typically used to indicate how popular a person is. So this large number of fake followers could have been used to influence opinion.
Now suppose we combine the twitter world and the lackadaisical voting populace. What if significant portion of the populace could be convinced that they were involved in the direction of government through the use of hashtags. Popular opinion could be "discerned" through the use of hashtags and followers of topics. Potentially, this belief could gain more and more "acceptance" by the population.
So where does that leave us. We would have a population that believes government is influenced by social media. That social media would be dominated by the political activists and includes significant numbers of "fake" people. Instead of debating issues, activists acting through many fake accounts could generate a false impression of popularity which is accepted by significant numbers of people. Taking it a step further and combining the push for electronic voting as "fair, equitable, and convenient". We could arrive at a place where elections occur through social media.