http://opendatahackdc.eventbrite.com/

International Open Data Hackathon DC Saturday, December 3, 2011 Free to attend

Wikimedia DC is one of the organizers. If you're in the Washington, DC, USA area, please consider attending! You'll meet participants from the Sunlight Foundation, Library of Congress, World Bank, and other institutions, and participants will discuss and design "solutions to make data more open and make better use of open data."