It's been a good couple weeks for Ruby IDEs. First, Ruby In Steel was released. Pretty much simultaneously, ActiveState releasedKomodo 4 with support for Ruby.
Komodo is a significantly "weightier" IDE and Ruby is just one of the many languages it supports. It is, I suppose, more akin to Visual Studio itself than to Ruby In Steel, which adds Ruby support to Visual Studio.
I still have much more head-to-head comparison to doing, but I wanted to point out a clear "win" for Komodo: the Ruby shell shown in the bottom pane here is graphical, allowing for a significantly easier cut-and-paste experience than the IRB-in-a-DOS-Box approach:
P.S. What the heck is "IDE_GeneticAlgorithm"? Well, a while back there was a flurry of posts about "the best" customized color schemes for programmers. I thought it would be funny to write a distributed genetic algorithm that "bred" color schemes and evolved them on the Web. The problem is the age-old challenge of creating a decent traversal through colorspace (that isn't along the gray axis). What's a way to encode color in a single number such that like values have like colors?