I'm very into flow-based programming because I use a fair bit of it for audio DSP and that's how I think. So these days when I look at code-as-text I often find myself thinking about how I'd like to see the functions, branding etc. abstracted out into a flow chart diagram automatically. I was just struck during the Demo (and from some previous explorations) at how good M. is at developing graphs from structural information, and I think to myself 'why not from code?'.

On a tangential note, this latest demo looks very very close to the sort of thing Bret Victor has been talking about over the last year or two (http://worrydream.com). If you haven't checked it out I think it might be interesting to you.