Second: I think where this will really shine is in the "twilight zone" of shell scripting. So often, I start off with a short chain of commands on the command prompt. I'll keep adding to the chain, until at some point I feel the need to move this elaborate chain (usually an alias at that point) into it's own script file. I could copy directly, but then any improvements would require continuing to use shell script (ugh). On the other hand, I could translate the existing script to Ruby, but then I'd have to put in the overhead to do the translation with no immediate gain.

With this, I could see doing a direct copy-->paste from command line to script file and just keep going...or better yet, since it's all Ruby, why not an extension on File to automatically write out X lines of history to a script file?

...oooooh! I'm excited already!