Is The Arab Spring Coming To The US?

One New York-based group is calling for the occupation of Wall Street in a demonstration mimicking the Arab Spring protests that resulted in a vast political shakeup in the Middle East.  Why?  They feel American policies are being dictated by corporate interests on Wall Street (I'm inclined to agree).  So they're going to be camping out in NYC until the democratic process is restored in the US:

On the 17th of September, we want to see 20,000 people to flood into lower Manhattan, set up tents, kitchens, peaceful barricades and occupy Wall Street for a few months. Once there, we shall incessantly repeat one simple demand in a plurality of voices and we will not leave until that demand has been met. Like our brothers and sisters in Egypt, Greece, Spain, and Iceland, we plan to use the revolutionary Arab Spring tactic of mass occupation to restore democracy in America. We also encourage the use of nonviolence to achieve our ends and maximize the safety of all participants.

I'm wondering how many people will actually show up?  Do you think that Arab Spring-style protests are feasible in the United States?  Would they be effective?