As I touched on in my recent review of the ThinkPad T400s, Lenovo updated the touchpad in the T400s along with everything else. To keep the thin profile desired with the T400s, there was literally no room for a recessed touchpad. To keep usability intact, they came up with a unique texture for the touchpad that would allow users to discern between the palm rest and the touchpad.

David Hill just published a blog post about the design process behind the touchpad redesign and has some interesting pictures as well.

Source: [Design Matters]