Dataflow environments like PureData, Max/MSP, Quartz Composer and vvvv are very much like 2D GUI-driven shells that handle various data types. Max/MSP was, at least, explicitly conceived as a sort of UNIX for multi-media. After working with such tools for years, I must say that the tools the professional programmers use seem comparatively quite primitive in many ways (though much more advanced in others). A graphical environment that utilized the same sort of dataflow model, but with a more general intended audience, more extensible architecture and some concepts from functional programming would have the power to really change how programming is done.