Software + Services (S+S) is a major initiative at Microsoft. S+S, as opposed to the more limited concept of SaaS, is all about combinations of local software and remote services interacting with one another. Local software leveraging remote services can create a better overall experience than either are able by themselves. The S+S architecture brings together the best of both worlds, maximizing choice, flexibility and capabilities.
The MSDN web site has added a new section to the MSDN Architecture Center devoted to Software + Services Architecture.
Check it out.