Thought y'all might want to see this webcast:

https://www119.livemeeting.com/cc/microsoft/view?id=JH3PH2&pw=NK3C8X

More info:

This session discusses utilizing capability built into Windows XP and Windows Server, to implement a logical isolation strategy. This strategy can help to better protect domains, servers and desktops, from rogue machine, infections and information theft threats.
The Microsoft Solutions for Security (MSS) team has released the first guidance for the selection of appropriate IPsec components and the first thoroughly documented prescription of how to implement.
The Server and Domain Isolation Using IPsec and Group Policy is available on TechNet
http://www.microsoft.com/technet/security/topics/architectureanddesign/ipsec/default.mspx