Hello Stephen,
Thank you for the interest in our RadControls for Silverlight.
I had a talk with our management and they are very positive about the idea of creating a control or a technology to support dynamic UI personalization for Silverlight similar to ASP.NET WebParts.
The first step in that direction is already done. Please have a look at our Docking for Silverlight.
The team developing Docking are currently working on state persistence functionality. This means that the control will support an easy saving of the current state and persistence of layouts tuned by end users.
Besides that, Microsoft have promised to add the ability to support dynamic styles for Silverlight 3.0 . This means any visual state properties and even behaviors may be easily set and persisted by building / setting custom styles runtime.
So I cannot promise (for near next releases) codeless support for personalization but I'm pretty sure with every next release such task will be more and more easier to accomplish with our controls.
Meanwhile I will make sure to elevate your idea so that the Silverlight team will put efforts in that direction.
We are always happy to receive suggestions and constructive feature requests. This helps us a lot on planning new controls and features as well as polishing existing ones. I have updated your Telerik points.