Why Does The Obama Campaign Have Gov. Palin's Social Security Number?

From the Politico:

Democrat Tony Knowles, her opponent in the 2006 Alaska gubernatorial race, put together a detailed, 63-page research document — obtained by Politico — cataloging Palin’s strengths and weaknesses. And the Obama campaign, in particular, knows Palin well: A key Obama consultant, Anita Dunn, worked on Knowles’ campaign.

Opposition research is nothing new.  This document though -- which was leaked to the Politico -- contains the first five digits in her Social Security number in violation of privacy laws.

Makes one wonder what the Democrats are doing with Gov. Palin's Social Security number.