Light Table got so much interest that they've applied to Kickstarter ... http://www.chris-granger.com/2012/04/15/light-tables-numbers/.
@Bas, @AndyC Part of the interest is the ability to move and organize things on a "drafting table" into logical groups that is free from the restrictions of folder/file structure. The instanteous feedback with sample data showing realtime results is like edit-and-continue, as non-edit-and-continue is to edit-and-continue. Also, edit and continue with graphics? Since this is based on (EDIT - name and link) Bret Victor's presentation, things like displaying change over time are also likely to be added as well. If you haven't seen that in action yet, I think you'll be impressed.