I've blogged about the Marshmallow test. Here's the video evidence. I still want to do this experiment on my niece. Why have kids, if you don't play with their minds?
http://vimeo.com/moogaloop.swf?clip_id=5239013&server=vimeo.com&show_title=1&show_byline=1&show_portrait=0&color=&fullscreen=1

Oh, The Temptation from Steve V on Vimeo.