For example, the work on tangible UIs eg- Self: http://www.selflanguage.org/
This is a good demo of what could be done in the Self environment: https://www.youtube.com/watch?v=Ox5P7QyL774
GUI and non-programmability are tangential things. I don't think they're implicitly bound together.
Why are terminals still based on the concept of a teletype? It is fully one dimensional. You have to fit all interactions through that one dimension. (Multiple terminal windows are a kind of hyperspace, I suppose.)
If only if you could easily pipe from one terminal to another.
[1] http://www.linuxjournal.com/content/using-named-pipes-fifos-...
Sure, the adaptive compilation is nice, and message sends and type inference, but how well do the UIs work?
It's sort of cool to see Urs Hölzle and Craig Chambers in the papers section.
As for what it "does", what does the smalltalk environment do? It's a combination of a programming language with graphical programming tools. It does anything it is programmed to do.
Given, it's not exactly usable for modern projects, but it's worth studying.