The first release of SharePoint Guidance from the Microsoft Patterns & Practices SharePoint Guidance team is now published on Codeplex at http://www.codeplex.com/spg.
Disclaimer: This will evolve (and change) significantly. At this stage the RI provides a basic set of WSS features with accompanying guidance. This is not a CTP or a BETA.
Stay tuned for new releases about every two weeks or so.