They are not a political party! Quite the opposite, they are protesting the entire political process. OWS is the modern peaceful version of the peasants storming the palace with knives and pitch forks and demanding change or else. Instead of knives and pitch forks these peasants have cellphones and civil disobedience. With a single tweet any of them has the potential to create a flash crowd of thousands. There are now over 1,000 Occupy protests worldwide.
A lot of people seem to have a romantic view of the movement. I am more skeptical. American's are understandably upset by some of the incestuous financial goings-on between government and big business. But most of the OSW types aren't rallying against crony capitalism and corporatism necessarily... they are after genuine capitalism. They are not so much against government manipulation and control of the economy, they just have a difference of opinion on who should benefit more or less. In other words they are A) happy to keep the same corrupt structure in place and merely change out winners and losers, and B) happy to kill off normal capitalistic ideals and processes in a broad swipe against bad/false capitalism.
There are strands of truth to the movement, but it's a VERY imperfect protest, egged on by many of the worst political partisans.