MS Security blog - you'll want to add this to your list
Jeff Jones is the director of trustworthy computing for Microsoft in the US and he knows his stuff when it comes to security.
I've been seeing lots of emails from Jeff internally on some of our DL's, and they've been very interesting.
Last week he finally started blogging some of the interesting stuff we've been seeing internally, so if you are interested in whats happening in the Trustworthy Computing team or in security in general - or specifically security with reference to Microsoft products, you'll want to pay his blog a visit. There are already some good posts there including some vulnerability graphs and trends.
Jeff's blog is at http://blogs.technet.com/security/.