Mil-oss.org is a site loaded with information you can use. If it has been a while since you have checked out this tremendous resource please return to the site and check it out. You will find news, context, information on policy, and tips on making the most of open source in military and government associated solutions.
The site is there to support a community and it also provides great info on how to get involved.
One of the most important ways to get involved is by engaging with others at the annual Working Groups. WG4 is coming soon (15-17 Oct). They have a tremendous line-up of speakers and and a great group of community-focused thought leaders attending. These folks need your brain in the game and would very much appreciate having you there.
Register to attend at: http://mil-oss.org/wg4