"You might have heard of Microsoft's Silverlight technology.
It's a rich internet application (RIA) framework positioned to
rival Adobe's Flash. Unlike Flash however, it's only available for
Windows and Mac, not Linux. This is where Moonlight comes in.
Moonlight is a project to create a Silverlight plug-in for the Mono
environment, which will run on Linux, Mac and Windows.
"Silverlight 1.0 was very much an early-stage implementation
and, at the time of writing, is in release candidate stage..."