What is this snapping brick for / which set is it from? I've found this DUPLO brick:



The red part can be pushed in and snaps out when the button on the top is pressed:



Any idea which set this is from or what it could be used for?
Looks like the Duplo Car Launcher and according to Bricklink this appears in at least 4 different sets: http://www.bricklink.com/catalogItemIn.asp?P=31080c01&amp;in=S