From the press release:
The U.S. Government Printing Office (GPO) expands its social media presence by joining Pinterest. Connecting people through 'things' they find interesting is the founding principle of Pinterest and a natural fit with GPO's core mission of Keeping America Informed on the three branches of the Federal Government. GPO will use Pinterest to share historic photos, videos, products, and Government publications with the public. Pinterest joins GPO's other social media platforms of Facebook, Twitter, YouTube, and Government Book Talk blog.
At the moment, there are 7 boards, including Apps and Featured Publications. But the coolest, at least to this librarian, is Historic Photos.