The upcoming Microsoft "Oslo" offering might be a bit vague to grasp, which I can readily understand. It has been perceived as a SOA implementation toolkit, but is rather focused on being a modeling (UML), management, and hosting platform for delivering model-driven service-oriented composite applications and S+S solutions; plus cloud computing through modeling. Read Loraine Lawson's Best Explanation of Oslo So Far for a rather typical experience.
Also look at the Oslo PDC sessions posted by Matt Winkler, on how "Oslo" is a service repository and a platform for both lifecycle management and hosting of services and processes. The service and process implementation tools in "Oslo" will be Visual Studio, WF, WCF, BizTalk, Zermatt, etc - and "Oslo" will be the one initiative to rule them all.
Directions on Microsoft on "Oslo": Messaging, Workflow Roadmap Announced (PDF)