Okay, a few of my scribblings from the Silverlight and Managed Code demos (and they haven't finished yet)...
New Visual Studio Orcas Silverlight Project Type
Create the XAML representing your application UI and a code behind (Page class derives from Canvas). Scott demo'd C# but any .NET language is supported. Full Intellisense support on Silverlight objects etc.
New ASP.NET Silverlight Server Controls
Host Silverlight applications in your ASP.NET web pages
CLR Cross Platform Debugging - *Woah!*
Scott showed attaching the Visual Studio debugger to the Silverlight app he'd built running on a Mac. Set a breakpoint and you'll see the breakpoint hit. You can inspect object properties etc on the remote application and even modify them. We saw the Mac update as Scott made changes. This is very cool and must have been incredibly challenging to do.
Connect to Web Services / WCF Services
Just like you would in any other .NET application.