Trustworthy Computing just released two papers on current issues:
Determined Adversaries and Targeted Attacks Whitepaper
This paper shares Microsoft's insights into the threat that Determined Adversaries and Targeted Attacks pose, identifies challenges for organizations seeking to combat this threat category and provides a context for other papers that will directly address each of those.
New MMPC Threat Report on Rootkits Now Available
Rootkits provide stealth capabilities to malware. This Microsoft Malware Protection Center threat report examines how attackers use rootkits, how rootkits function on affected computers and recommendations that can help organizations mitigate the risk from rootkits.