When I first saw the name of this political party, I honestly thought it was a joke.
The United States Pirate Party is the American version of a political party formed in 2006 in Sweden.
Their platform focuses on issues such as the Right to Privacy, the Right to Government Transparency, the Abolition of Digital Rights Management, and the Abolition of the idea of Copyright Infringement.
After reading a bit about them, it actually sounds like they are a group of people angry about lawsuits for online file sharing.
The Chairperson of the Party is Brittany Phelps.
From what I can tell, they have not actually ever ran a candidate for office but in the 2010 elections they are endorsing a guy named Michael Meo for Congress in Oregon. Mr. Meo is actually a member of the Pacific Green Party (the Green Party for the State of Oregon).
You can read more about them at this Wiki article as well.