There's no native Silverlight support but we have this custom app on CodePlex:
Convert PowerPoint slides to Silverlight presentation in webpage:
It's a separate app, not an add-in and shouldn't need PowerPoint installed since it simply consumes and exports files.
The app converts PowerPoint slides to a silverlight web page
Note, if you run this on 64-bit Windows there's a way to get it to work. By default it opens in 64-bit Internet Explorer and will ask you to install Silverlight even if you have it installed. You just need to open a new regular Internet Explorer window (not a Internet Explorer 64-bit) window. If you still see the Install Silverlight image in 32-bit IE then install or check the IE add-ons to make sure the Silverlight add-in is enabled.
As for inserting Silverlight content into PowerPoint we don't have native support. I've heard that the Silverlight ActiveX Control is the way to go but just tried it now in PowerPoint 2010 RTM and got a Microsoft Visual Basic for Applications error: "System Error &H80004005 (-2147467259). Unspecified error".
The only conceivable workaround is to insert a Microsoft Web Browser control in PowerPoint and embed the whole web page that way. http://support.microsoft.com/kb/291926 describes how to embed use the Web Control in PowerPoint.
Note: This won't work with PowerPoint 64-bit because it'll use the 64-bit IE and there's not a 64-bit Silverlight version available.