We had something similar quite a while ago at Naughty Dog, when working on the Jak and Daxter PS2 games. Our development environment was Emacs, and as well as having a REPL console in one of the buffers, you could position your cursor inside any function/method, hit CTRL/T, and have just that function compiled and updated on the target hardware, on the fly, with no restart required.<p>Iterative programming is especially suited for game development, where you want to rapidly experiment with tweaking parameters and behaviors without waiting for a full compile/link/download/restart.
This is really cool!<p>I wonder if people are working on autocomplete packages for different IDEs/editors to help make RubyMotion smoother with those long method names (didn't see much googling it). IMO in combination with this, autocompletion would make RubyMotion a tremendously compelling option for iOS development.