I'm currently investigating the features of SharePoint Services for a collaboration repository. Particularly, I've been looking at the extensibility and integration aspects of SharePoint. The SharePoint SDK (download) documentation file, which is all that is in the SDK, has plenty of hows and wheres but is very light on any whats and whys.
This TechEd 2004 slide, from the presentation Programmatic Access to SharePoint Lists and Document Libraries, is a great matrix of what the different avenues of programmable access deliver. The avenues are:
- Object Model
- Web Services
- WebDAV
- FrontPage RPC