Description of the different hosting solutions from Microsft

FYI - here's a short description of the current offerings from Microsoft -

Windows-based Hosting
The Microsoft Solution for Windows-based Hosting version 4.0 provides a highly efficient operating platform for service providers of all sizes. The solution includes tools and partner applications that Web hosters can take advantage of to develop and deploy in-demand customer site features such as blogs, forums, and photo galleries.

Hosted Messaging and Collaboration
The Microsoft Solution for Hosted Messaging and Collaboration version 3.5 enables service providers to host enterprise level e-mail and collaboration services for small and medium-sized businesses. Service providers can deploy value-added services such as team site hosting, instant messaging, and hosted mobile messaging for mobile device users - along with Exchange-based mail services.

Windows-based Hosting for Applications
The Microsoft Solution for Windows-based Hosting for Applications version 1.0 takes advantage of the Windows infrastructure and operations platform to enable ISV application hosting. This solution is focused on helping ISVs expand revenues and markets by taking their on-premise applications online as a hosted service.

Hosted Microsoft Dynamics CRM 3.0 Solution
The Hosted Microsoft Dynamics CRM 3.0 Solution is a Windows-based solution that enables service providers to capitalize on the growing business demand for customer relationship management (CRM) services. This solution enables service providers to host the Microsoft Dynamics CRM 3.0 application - a full-featured CRM product that is beyond the abilities and resources of many smaller businesses to deploy and operate.

Source - Windows Based Hosting 4.5 beta documentation.