Being everyday asked by hosters to help them understand how they could climb the value chain with MS, I know that SaaS vision provided by Redmond is compelling.
So far, implementations and directions from the "blank" page have been few, especially on the evangelization side, where "simple" is key to attract. I think the works published by GianPaolo and team, at http://www.codeplex.com/LitwareHR, really makes sense, as it's delivered with different levels of technical and not-so-far-from-funcitonal videos.
So have a look at it, and also continue to visit MS reference sites on SaaS:
- for BDMs, ISV CEOs and strategists: http://www.microsoft.com/saas
- for Architects, Product Managers, Developers: on MSDN at http://msdn2.microsoft.com/en-us/architecture/aa699384.aspx
- for Ops, hosters, resellers and everyone who wants to enter prod soon: Microsoft solution for hosting applications, at http://www.microsoft.com/serviceproviders/solutions/applicationhosting.mspx