So far I've seen freeRIDE, Practical Ruby, I think one called RubyIDE and
another whose name I can't remember.

The fact that there's this much interest is a GOOD thing, but I'm just
wondering how these efforts could piggy-back off each others work or even
ideally combine <although I know this is hard due to conceptual design
differences between the projects' founders>

If nothing else, what about a common architecture for plug-ins?

For those IDEs that are trying to map to different GUI abstractions, what
about a re-usable GUI-agnostic API?

Just wondering.  I'm not contributing to any of them (I must admit I am
only beginning to really learn Ruby.  All my cycles are being eaten by
Java which I'm in the intermediate stages of learning for work) so this is
by NO means a gripe or demand, just wondering what people's thoughts are.

-Chris