You define the animation effects by setting the control's effects() property. This should be a dictionary of CSS properties that can be animated with $.animate(). The position and size of the content can be animated without moving adjacent elements in the document flow; while the mouse is over the content, the control leaves a placeholder element of the content's original size to hold the shape of the surrounding elements.
To animate color properties (as shown in the demo), include a plugin such as Color Animation.
This control was discussed in a user interface blog post.