Long story short, IPsec isn't just for VPNs anymore. While IPsec is popular when used in conjunction with virtual private networks, the technology has reached a level of maturity that now allows it to be used for basic packet filtering and other isolative security practices.
Windows Server 2008 takes some steps forward when it comes to broadening the reach of IPsec. Let's look at the ways Windows Server 2008 takes steps to broaden the reach of IPsec.
Correcting the befuddling deployment process: Traditionally, configuring IPsec has been, shall we say, less than easy. It involved a bizarre deployment and configuration process and a non-intuitive console interface. Microsoft answered the cries of administrators everywhere by releasing the Simple Policy Update for IPsec. This update, for Windows XP and Server 2003, was not well-received when it came out in 2006, but it certainly is a step forward. You can find this update in Windows Server 2003 Service Pack 2.
With the release of Vista and now Windows Server 2008, the configuration console for IPsec has melded with Windows Firewall, making it infinitely easier to correctly deploy IPsec policies in tandem with other technologies. For instance, the addition of the "New Connection Security Rule Wizard," is really useful for getting any type of IPsec configuration correct, be it an isolation policy, a tunnel or server-to-server filtering.
Server and domain isolation: IPsec's somewhat hidden strength, however, is its built-in capability for shielding legitimate machines on your network from communications with machines that (a) are not managed and (b) are not authenticated. IPsec can require authentication, based on Kerberos, certificates or pre-shared keys, and enforce the presence of those factors before it allows actual communications between two machines. This is enormously powerful in the context of server isolation -- it's a sort of pre-Network Access Protection (NAP) way of ensuring that your most precious machines on the network aren't being threatened by zombie PCs that come on the wire.
Windows Server 2008, Win2K8, WS2008, Windows Server, IPsec, Improvement, Features