Very cool stuff. From what I've read, I gather that the actual keysets developed by Engelbart's team for NLS differed a bit in style from the one in that link,

Very cool stuff. From what I've read, I gather that the actual keysets developed by Engelbart's team for NLS differed a bit in style from the one in that link, but more interestingly/importantly(?) could also provide haptic feedback by puffing air up from under the keys. (i.e., as a very basic example, one could mouse over a toolbar button and the keyboard might provide a physical cue by bumping the "hotkey" for that given command - immediately teaching the user how to bypass using the mouse next time).