Couple days ago Chris Grangers posted Light Table - a new IDE concept (inspired by Bret Victor - Inventing on Principle presentation) , and its Light Table's numbers follow-up post shows how well his ideas where received by the developer community.
In a way a number of these concepts are already present in the latest version of O2 and its REPL C# environment (note to self: start blogging about O2's scripting environment)
These two videos are well worth the time to see them
Chris Grangers - Light Table
Bret Victor - Inventing on Principle
