Image provided by: Natrium42Here is what the autor writes:

The touchscreen controller in the DS allows to read out pressure of the touch. It should be called pseudo-pressure, really, because it’s based on the the touched area and not on real exerted pressure.

Here is a small demo to show touch pressure. Although an emulator binary is available there is no much use to it.

http://www.dslinux.org/blogs/natrium42/