[Edit: Sign up to join us here (Facebook event)]

The California Codes Hackathon, now scheduled for September 17 in San Francisco and Denver, is gathering steam.
In addition to the excellent hackers who've signed up to prepare data for the hackathon (check out the wiki), supporters now include:

Sunlight Foundation (thanks, Laurenellen McCann and James Turk), Common Cause (Philip Ung), Nation Builder (Adriel Hampton). We'll be announcing more soon...
Sign up now to join us: Facebook Event or through NationBuilder (same list).