Thank you for the question.
WebUI Test Studio will support OOB Silverlight application very soon -- we are about to present it with the 2010 Q2 release in a few days. Take a look at this thread
listing what's new with the upcoming release.
the Telerik team
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Public Issue Tracking
system and vote to affect the priority of the items