The two most important new social movements in the United States in the last decade have been the Tea Party movement and the Occupy movement. The former is, to this point, much more important than the latter.
Both of these are reactions to the state of American government and society today. Both are upset with the status quo, but wish to change it in different ways. The Tea Party movement wishes to move America towards a society with less government intervention in the economy. Some parts of it also hold beliefs similar to those of the religious right (which can be seen as a social movement of its own, but one that arose much longer than ten years ago). By contrast, the Occupy movement is much more of a left-wing movement that identifies the rich (and the influence they have on government) as the major problem faced by the country.
There are other social movements in existence today, but these are the two most important which have started in the last 10 years.