JaySch

LightSwitch does not have built in support for using persisted CLR object from disk as a datasource.  We're working on a blog series that goes deeper into the underlying architecture of a LightSwitch application over on the team's blog: http://blogs.msdn.com/b/lightswitch/archive/2010/08/06/the-anatomy-of-a-lightswitch-application-overview.aspx

Thanks

Jay

LightSwitch supports development in both C# and VB .NET.  LightSwitch applications can be run in the Silverlight 4 Out of Browser host or hosted within the browser.

Silverlight only for the client applications at this point.  We do support creating an out of browser client application (in fact that is the default) which runs in the extended sandbox giving the application access to desktop resources (file system, devices, COM interop with other applications). 

LightSwitch uses the ASP.NET Membership/Role system under the covers.

LightSwitch does not generate XAML files that can be manually edited.  We compile the screen definitions (and the rest of the application components) into assemblies.

No plans currently to integrate PivotViewer.  Integration would be via the custom control extension point you mention.

We focused on the ability to control the functionality of the application and/or implement business logic and rules based on the current user of the application.  In LightSwitch you define the set of permissions ("CanApproveOrder", "CanPromoteEmployee") you need and write code to implement your custom logic based on those permissions (User.HasPermission(CanApproveOrder)).

LightSwitch applications include built in support for creating and managing the user->role and role->permission relationships.