US-CERT

Here's a link to the US-CERT Web site. You can join a couple of technical mailing lists here to track security issues. From the home page:

US-CERT, a partnership between the Department of Homeland Security's National Cyber Security Division (NCSD) and the private sector, has been established to protect our Nation's Internet infrastructure. It will do this through global coordination of defense against and response to cyber incidents and attacks across the United States.