As I read through the sforce description (for the third time), I realized that Salesforce.com was attempting a hybrid WSP offering. In essence, they were going to offer:
1. ISP services (a hosted infrastructure, bundled)
2. WSP Extensions (Tooling like WebLogic and .Net services)
3. Horizontal WSP offerings (their SFA, plus partner offerings)
4. Horizontal WSP Service Framework (their base utility services)
What seemed missing from the sforce picture was the "base WSP" offering. That is, the whole infrastructure around creating a managed web services offering up. I'll have to dig deeper, but the initial documentation focuses on building custom applications (SFA-ish) using services.
After talking with some of the sForce partners, I got the feeling that they didn't really understand what sForce was all about. Personally, I think it's an interesting idea, but it seems like they missed the whole "common infrastructure" part of the problem. Perhaps they'll circle back?