Have you tried KDevelope 3.4 for Ruby dev?
Is it any good?
It’s ok. You can run non-interactive ruby scripts in it and the syntax
highlighting works o.k. But that’s already all.
I guess a normal Kwrite session would be enough for small projects 
[email protected] wrote:
Is it any good?
I am using KDevelop for Ruby and Rails, and it’s integrated extremely
well with KDE, Kommander, Korundum and QTRuby 3, and of course CVS and
SVN. However, I’m using KDevelop 3.5.6 and all the underlying packages
are either 3.5.6 or the required dependencies for 3.5.6. I haven’t
attempted to work with 3.4 at all. KDevelop is rather large, though, and
pretty much limited to Linux and for all practical purposes KDE and Qt.
If you have a different idea of what a Ruby application should be like
– Windows or Mac, a different desktop, or a different GUI toolkit –
you’re probably better off with something else. Free as in freedom
doesn’t always mean convenient portability. 
M. Edward (Ed) Borasky, FBG, AB, PTA, PGS, MS, MNLP, NST, ACMC(P)
http://borasky-research.blogspot.com/
If God had meant for carrots to be eaten cooked, He would have given
rabbits fire.