Obama (and of course Hillary Clinton) have been subject to internet memes. A meme is any unit of cultural information, such as a practice or idea, that gets transmitted verbally or by repeated action from one mind to another (Source). An internet meme is one that is transmitted mostly by internet. A whole field of science has arisen concerning how memes evolve and how they vary, mutate, compete, propagate (inherit), and become extinct.

Stories about candidates, whether true or false, are memes. The stories about Kerry having lied about his experience in Vietnam were memes, first propagated by television ads and then sustained by internet and talk shows for months. The traditional way to countering memes is to confront the source and shutting it down before it reaches too many people. However, internet memes spread too quickly and cannot be shut down. They were never able to stop them and thus now famous adjective "swift-boated".

There is several ways to stop a meme, that is to start a counter-meme that contradicts the first meme and makes it irrelevant, unimportant, or unimpressive. It is important to get to the target audience first or faster and "vaccinate" them before the the undesired meme or viral idea reaches them. In this sense, the detection and elimination of viral ideas is not different from epidemiology.

These are some ideas that are now being discussed in the field of memetics. In April 2006, Dan Noe wrote a series of articles on Memetic Warfare (Source). One of the strategies that he describes sounds a lot like what Obama is now employing with the evangelical Christians in the wake of the Wright fiasco.

http://danzarrella.com/how-to-stop-t...of-rumors.html
Much like seeding is an important concept in meme spreading, it is equally important in the control of memes. In an article titled “Memetic Warfare“, Dan Noe describes a clever way to identify and immunize individuals who are at high risk of being exposed to the target meme:

A possible way of keeping the number of competitors small is to lay traps for those who fit the psychological profile of a potential competitor. For example, seminars could be advertised that would appeal to people like them. Then, when they arrive, carefully present the material in such a way as to discourage them from continuing (or beginning) in their meming.

The Obama campaign seems to have taken this advice (if unconsciously) by specifically targeting the faith community on the Fight the Smears page with a call to action for supporters to send letters to the Evangelical community:

Take a few minutes to write a positive and respectful note asking members of the evangelical community to discourage the use of personal attacks and prejudice to divide Americans.

The faith community in general and the traditionally conservative Evangelicals in particular have been a rich source of hosts for anti-Obama memes and targeting them with contact immunized supporters seems a good way to begin to stem the tide.

The science of memetics provides a wealth of information that can be used by political campaigns (and other entities) to fight negative rumors and the Obama campaign, while perhaps not using this body of data overtly, has taken a large step forward towards a memetic immunization strategy with the new micro-site.