With this jQuery plugin, you can extend the animate function to support the CSS box shadow-property. You can animate the color, the x- and y-offset, the blur-radius and spread-radius.
In the code, the x offset and y offset are referred to as left and top. However they actually behave contrary to expectations: a value of +10px for top will place the shadow 10 pixels below the box. Instead the behaviour matches the CSS properties right and bottom.