I just read Wayne's blog entry where he talks about this concept and at first I did not understand it. I then looked at the referenced project and cracked open the yummy.groovy file and I finally understood the concept(I am one of those tangible learners).
Since the yummy.groovy file is a script, the contents for that view can be dynamically changed at runtime! You could theoretically write an entire UI with many “screens” in a single Eclipse view using this technique. By having the contents of your view be in a Groovy script you can “swap” out the contents at runtime with a new script.