Acknowledgements: Special thanks to the following for comments on this paper: Mike Graves, Steve Cisler. Thanks to everyone who has put up with me going on and on about WorldBoard for the past year; you indulge me well. Special thanks to everyone in the Learning Communities Lab, your ideas and technology contributions have really made a difference, but our growing sense of community means the most. Thanks to Eileen Genevro who created the WorldBoard graphic. Lee Wood has been collecting WorldBoard scenarios, and generating many of his own. Sunil integrated my accelerometer into the Mac serial port, thanks! Thanks to Robin Myers and Mike Clark for hardware and idea help (I need lots more!). Dan Russell is a fountain of helpful ideas and pointers. Gregory Abowd for good conversations. David Ditz for being a great "Info Scout." Thanks to Doug Solomon for his corporate development perspective. And of course, Don Norman for continuing to pose imagination challenges of his own, constantly urging all of us to think beyond the desktop. Alan Kay's notion of a Dynabook, as well as his many other insights, have been a tremendous inspiration.