I gave a Ruby talk here at Guidewire a few weeks ago, and it has been fun to see all the discussion that it has generated. I don't think there is much chance of us using Ruby in any serious way in our core applications, but it could make inroads in the periphery (support code, example integration applications, etc.)

Despite how much I love Ruby, I'm still skeptical of how well it will perform in a large system. I just don't have experience with large, dynamically typed systems, and a lot of older engineers I respect shudder at the idea. Maybe the prevalence of unit-testing will change this (Martin Fowler seems to think so.) I guess we will have to wait and see how the Rails projects turn out to provide evidence one way or the other.