I've actually started working with some Code for America folks here in my community - independently of CfA - on some city open data projects. They're awesome. :-)
What are the security and nda requirements? I recently got an invitation to a show and tell meeting (a recruiting event) but I didn't end up going. I'm afraid of having to sign onerous agreements, similar to a "never tell anyone that this was bad". I unfortunately fell victim to that at a startup, and I want to maintain my freedom to praise or criticize the government and politicians as appropriate.