SharePoint [2010] as development, composition + application platform

I consider SharePoint having 2 distinct faces:

1. It's in itself an application, with lot's of end-user oriented functionality. This is true for the foundation WSS, and significant more for the licensed version MOSS 2007
2. It's a rich development and runtime application platform, to host your own custom developed applications.

Being primarily development-oriented, it will be clear that personally I like SharePoint best for the second role.

I'm not alone on this. More and more custom company-internal applications are based on and within the SharePoint platform. SharePoint comes out-of-the-box with a well-filled toolbox of both technical as functional building blocks. Developing custom SharePoint applications is therefore a combination of composing and customizing OOTB SharePoint building blocks, and augmenting it with custom developed functionality in which the SharePoint platform does not standard delivers. This implies a significant mindset switch for [old-school] application developers. Instead of the default decision to custom build all application parts, the SharePoint best-practice approach is to first consider the OOTB building blocks. Can you deliver the custom-requested functionality on sufficient level via the application of the standard SharePoint blocks? If so, choose that path. This composition-based approach will gain you in the initial application development stage. But even more it will be cost-benificial within the application maintenance period. It's better to have Microsoft fix and improve on standard building blocks, than have to do it yourself on your own proprietary ones. Of course, this principle can especially be applied on the more technical functionalities. And this gives you more time and relative budget to focus on the differential functionality for your company.

David Chappell has written a conceptual white paper highlighting the application platform aspects of the forthcoming SharePoint 2010. You can download it on the Microsoft site, SharePoint 2010: Developer Platform White Paper.