Light up the Web
Silverlight (codename WPF/E) is Microsoft’s answer to Adobe’s Flash (estimated to be running rich web based experiences on 95% of the world’s PCs and Macs). The goal is to provide the most natural and seamless method with which to design and build rich applications that transcend both desktop and web platforms. With innovative designer tools (Expression) that work easily with proven developer tools and technologies (Visual Studio and .NET) we are providing a compelling reason to develop using our tools and on our platform.
The uptake of Silverlight is going to be driven by content. The more experiences that are created with using Silverlight, the more people will download it - that's the way Flash got on 95% of the world's client computers.
There's also a nice looking website that's been created over here which gives more information on the technology and provides links to tools and resources with which you can get started.