I actually hacked up a half-baked version of this the other month, and it's been sitting around waiting for me to polish it or to find something better. And now here's the better, polished version ready for adoption.
Oh, this is nice. I've felt that other "command line utility" libraries for Ruby have been way more complicated than they needed to be. I'm converting some of my simple Ruby scripts and utilities to this to give it a try.