The Dynamic Datacenter Alliance blog has several posts now on a private cloud solution that Microsoft will be offering in early 2010 called the Dynamic Datacenter Toolkit for Enterprises. It will be a free, extensible toolkit offered by Microsoft that provides private Infrastructure as a Service cloud built on Microsoft System Center and is being developed in cooperation with Avanade.
Read up on it here:
http://blogs.technet.com/ddcalliance/archive/2009/09/28/dynamic-data-center-toolkit-coming-to-an-enterprise-near-you.aspx
-Rob