Microsoft has long sought to take control of the Web formats, protocols and itnerfaces implemented by their software systems, developer frameworks and services. The Silverlight-XAML combination is a dramatic break for the past routine of implementing corrupt extensions of W3C standards. The WPF set of technologies represents a clear alternative to the Web formats, protocos and interfaces the rest of the Web uses. I would also say that Microsoft's limited support of DOM, JavaScript and CSS in IE8 will act to "limit" the complexitiy of documents non Microsoft servers work with. This carves out a "complexity" niche for Microsoft systems. For instance, consider the complexity of MSOffice documents. IE8 will be able to fully display an interactive-collaborative computing interface for MSOffice-OOXML docuemnts converted to XAML. IE8 will not support a CSS-DOM-JavaScript representation of these same documents. The proprietary Silverlight-XAML docuemnt model will break the Web because of the integration with 95% of the world's business desktops.

WebClient?

Nine Silverlight Features that will Break the Web: 1. HTML DOM Integration 2. JSON Serialization 3. Styles and Templates 4. Local Storage 5. Databinding 6. Generics 7. ItemsControls 8. Layout Management 9. WebClient