The demo controls available on the website are very much like the Silverlight 1.1 alpha controls that were on the site earlier. Since Silverlight is still evolving we decided that releasing something that is sure to change in the future would not be a wise thing to do.
We offer no support for the Silverlight demo controls on the website since technically nothing has been released yet. So the API is there to change as well as the architecture and the styles/templates of the controls.
As for the simple color changes - there are several approaches for that. One way to do this is to add all the needed properties for the colours in the control. This generally works for things like "Foreground" and "Background" but is not very clever. We are looking for a way to easily alter all the colours of the controls in an application - e.g. it would be as simple as changing a Colour resource in your Application.Resources.
Silverlight currently has some issues with that but we hope that they would be resolved by the next release. So yes - you would be able to change the colours but possibly this would not happen at runtime and the change would be application-wide.
You can expect a CTP release in mid-May.
The kind of feedback you give us is very important for us since we would be able to match our goals and your expectations and get the things right from the start. So if there are any other things that you consider important do share them.
the Telerik team