"Empower people through great software at any time, at any place, on any device." (Bill Gates, 2000)
Seven years ago we still have the same question, if it will really run on any device. Microsoft is doing his best to support more and more Web browsers and devices. Today Silverlight supports  following "devices":
- Windows Internet Explorer 7 - Mozilla Firefox 22.214.171.124 and 2.0.x
+ Apple Mac OS X: - Firefox 126.96.36.199 and 2.0.x - Apple Safari 2.0.4
Support for Linux will be added if there is any need, but currently not on the roadmap as far as I know. Windows Mobile devices will be supported, but I think it will not be ready until MIX07  which already starts in a week. I would be happy to see Silverlight running on my Windows Mobile devices.