Silverlight is a lightweight browser plug-in that frees your code from the traditional confines of the browser. It is a rules-changing, groundbreaking technology that allows you to run rich client applications right inside the browser. Even more impressively, it is able to host true .NET applications in non-Microsoft browsers (like Firefox) and on non-Microsoft platforms (like Mac OS X).

Silverlight is evolving fast, and you need a reliable guidebook to make sense of it.