In his well-known book Going Public, political scientist Samuel Kernell argues that modern presidents have the ability to move legislation by appealing to the people directly rather than negotiating with members of Congress. This strategy of "going public" has its limitations, as he acknowledges, but it can also be a powerful strategy for forcing Congress to move along with the tides of public opinion.
A story today on ABCNews points out that President Obama is using social media tools, such as Youtube, Flickr, and Facebook to sidestep traditional media outlets and speak directly to the public. This seems to be a new sort of "going public" that not only ignores Congress but ignores the media, too. How effective this strategy will be remains to be seen.