I finally got a chance to update both my Mix 2009 and bitmap samples to Silverlight 3.  See the table below for links to the running samples as well as Silverlight 3 sample source code.  Note the GIF decoder has been updated to support interlaced GIFs (thanks to Paul Tallett for the source).


Silverlight 3 Sample Live Sample and Source
ICON/ICO Decoder Live Sample, ICODecoderSample.zip
WriteableBitmap with Media Live Sample, BitmapSample.zip
BMP Decoder Live Sample, BMPDecoder.zip
Bouncing Balls (LocalConnection) Live Sample (requires popups), BouncingBalls.zip
Chess Wars (LocalConnection) Live Sample, ChessWars.zip
GIF Decoder Live Sample, GIFDecoderSample.zip
Local Chess (Out of Browser) Live Sample, LocalChess.zip
Mandelbrot (WriteableBitmap) Live Sample, Mandelbrot.zip
MediaFlow (Perspective 3D) Live Sample, MediaFlow.zip
Effects Sample (Pixel Shaders) Live Sample, MoreEffects.zip