There are two great analysis of the same piece of improved rootkit malware, Hiding the Unseen at F-Secure's Blog and Raising the Bar: Rustock.A and Advances in Rootkits at Symantec's Blog

Another interesting recent discussion on improved rootkits from Joanna Rutkowska. I can't wait for her to release this. The comparison to SubVirt is key. BluePill on InvisibleThings
-toby