Moonlight – Mono
Silverlight 1.1 (http://silverlight.net) is a new development technology for the Web created by Microsoft based on the CLR that augments it with a 2D retained graphics system and media playback engine and ships a subset of the standard .NET libraries. Currently the Moonlight project supports both Silverlight 1.0 (canvas browser-based scripting) as well as 1.1 applications (canvas ECMA CLI powered execution engine).
Building an open source implementation on top of Mono is an obvious choice as Mono has most of the technologies required to implement it but is missing a few components. In this page we will track the work required and the design decisions involved in creating an open source version of it.