Don and Doug have started dropping hints about what they're going to talk about on the topic of Oslo for PDC. If you haven't read the other articles, the essence of Oslo is that it is a system for modeling applications that works throughout the entire lifecycle of development, deployment, and management. A modeling system encompasses many things but the key deliverables divide into a language for describing models, tools that build models, tools that use models, and a repository for storing models. You'll start seeing all of these types of components as betas of Oslo become available.
What Oslo doesn't change is what your services can actually do. There's nothing forcing you to start modeling your applications to make use of features in the Microsoft frameworks. Modeling is a tool that is supposed to enhance the productivity of developers and IT professionals rather than be the single way to do things. You're going to hear a lot about Oslo because it's new, but we're still planning to make the next versions of Windows and the .Net framework awesome. In the two years since Indigo has shipped, I've spent a few weeks working on Oslo and the vast majority of the time making WCF and WF better.