As a user, any standard components that will allow me to view a web page as intended on my IT is welcome.

From a developer perspective, it appears Silverlight is a little more optimize than Flash. The footprint is smaller and more developer friendly (free IDE, supports IronPython, IronRuby, C#, Javascript, VB).

Besides, if M$ didn't put out Silverlight, I'm sure someone in this community would port Moonlight (Mono's version of Silverlight) over.