In some of my classes, I have students do Venn diagrams as a way of organizing ideas while planning to write, but some of them have trouble with the concept.I now have one that they may be able to understand. The younger students may not recognize it as a joke, however.
Looks like I'd better start 'twittering'.
It's a funny diagram and the coolest thing about it - it was generated by the social media community and ditributed by twitter and blogs. A community that can laugh at itself has got to be a great thing.