http://academicearth.org/lectures/user-interface-i-alan-kay It will start about 23 min 30 s. Did you, developers, 've seen GRAIL before? Some of the things are just beautiful there, like basically drawing whole thing, not interferring and switching between mouse and keyboard (which annoys me in PD).
Cheers, Luke
PS. Also it is worth looking around 10 min 30 s - 17 min - just so futuristic.
PS2. Whole lecture in two parts is really worth looking at :)