Over the last several weeks I've been reading a lot of Richard Bejtlich's material - books and blogs. Richard is a frequent Black Hat speaker and emphasizes network security monitoring. He officially lists himself has "Director of Incident Response, General Electric", but has been a former Air Force intelligence officer (described as a soldier who protects national security data.)

He's posted a good essay on using open source security tools and specifically open source infrastructure like OpenDNS in order to battle large malware threats like Conficker.

I really like Bejtlich's way of thinking - particularly his NMS framework he writes about in The Tao of Network Security Monitoring. He's got several other books which I own but haven't plowed through yet, but I can highly recommend:

"The Tao of Network Security Monitoring: Beyond Intrusion Detection" (Richard Bejtlich)