I get a lot of questions about how to find out more about SharePoint hosting. So here's a shortlist of links to some content that should go a long way to helping you build Multitenant Hosted WSS platforms...

http://www.microsoft.com/technet/serviceproviders/default.mspx is the home for all hosting solutions. There is content in both the HMC 4.0 solution on how to plan build/deploy Shared WSS and in the WBH solution.

http://www.codeplex.com/SharePointHosters Brand spanking new solution kit for SharePoint

http://learn.iis.net/page.aspx/31/shared-hosting-roadmap/ There is some WSS guidance in the Shared Web hosting guidance on IIS.NET also very new.

For Portal Server (MOSS 2007) we don't have any official multitenant guidance as yet, but I do know a few hosters who have this working today, secondly some of my colleagues have cracked this chestnut and are now working on creating the MPS providers to get a fully MPS provisioned solution working for MOSS. This guidance will be released probably towards the end of the financial year... Juneish – I don't believe this will be fully standard hosting solution though... more a whitepaper and demo.