Automation UI Test tool(Like selenium webdriver) for Silverlight webapp

Any pointers to any open source tools for testing Silverlight webapp.

I've gone through the net and so far found Telerik which isn't an opensource and Silvernium(Selenium+Silverlight) project.

But there aren't much people using Silvernium.

Are there any other options on going around with testing the Silverlight application apart from the above two?