I don't know how many ideas like this exist but they do. I have been thinking of starting something similar like Light Table but primarily as a tablet IDE environment concept.
Here is why they will become standard in my opion:
I believe concepts like Light Table are import to future program development. Reasons why I do are because, with a growing number of programming languages and libraries, documentation becomes increasingly important. Especially with the need to perform cross platform and language task. One thing many programmers know is that it is difficult to read some APIs if not most, and there is no real great consistency to them. Ideas like this will help create standards much like ANSI did for C.
The need for screen space on tablets will change the scope of how IDEs display information too. I do believe we are on the path to be a tablet generation; mobile programming will become growing task as this happens. A couple example of what I mean; situations when a client needs you at their office looking though files with them so you understand what they need in a small processing app. Another could be because programmers get a sore butts from sitting to long; many of them would love to travel ( tremendous upside to innovation could come from this ). There are many reasons I can think of why mobile programming is gonna become increasingly an important feature.
Why it doesn't just happen:
There is a term I am sure most of you have heard " re-inventing the wheel " and have probably even been told not to do it. There is merit in this statement but it isn't solid. Programmers have created higher level languages ( modern practices ) to ease the learning curve and the same goes for libraries to those languages. When you need to minimize the space being used and code being compiled you may have to enter into lower level languages ( older practices ) to have the best performance and power in your app.
So I don't deviate to far from my point, what this means is programmers are not completely ready to reinvent the wheel. Some IDE's are very difficult to learn and programmers have had to spend huge amounts of training time into using these as efficiently as they can to become faster and better programmers ( older practices in a way ). To re-invent the wheel for IDEs they will have to add modern needs like tablet orientation or better documentation features ( newer practices (or needed)). In addition many IDEs have only become what they are due to many years of developing them to meet the needs of programmers.
In short they will come ( I really want to start this an open source project for my above idea in my opening sentence. ) but in due time ( which is soon ).