It has been a long long time since Terence Tsang last posted a Flash vs Silverlight comparison. And now that he is back, he introduces the Blur Animation Effect.
The effect is simple, the star icon in the application will follow your mouse position. While star icon is moving, the residue image will fade out steadily. Traditionally, this kind of effect is done by creating a lot of instances with different opacity. The consequence of this method is that it will consume you a lot of computer resources and hence limiting the level of effect.