Unintended Singleton

http://msdn.microsoft.com/en-us/library/cc903961(v=vs.95).aspx

VisualStateManager

...note that a well-designed control should generally handle its visual and behavioral states through VisualStateManager. http://msdn.microsoft.com/en-us/library/system.windows.frameworkelement.onapplytemplate(v=vs.95).aspx

Spline Keyframes

Tool here to calculate the first and second control points of Bezier curve used in a SplineDoubleKeyFrame

Asynchronous Silverlight

Silverlight 2 web services still have thread affinity with the UI thread, it's just now there is some behind the scenes processing taking place. When a web service call is made, it is placed in a queue to be actioned by the UI thread. ...  Once the call completes the ...Completed handler is invoked on the same thread that the ...Async call was made. 

This is with regard to the proxy generated by the WCF service reference wizard.
http://www.codeproject.com/Articles/31018/Synchronous-Web-Service-Calls-with-Silverlight-Dis