I was referring to Ruby-specific debugging solutions, such as gems or other libraries that log debug info, allow "break-points," etc.
I know about lots of text editors and IDEs with stdout/stderr capturing: Notepad++, Programmer's Notepad, Eclipse, etc. My personal favorite is UltraEdit, but I didn't suggest it because it's commercial.
EDIT: I just stumbled on this:
http://eightbitraptor.com/posts/debugging-rubyI still haven't used it, just passing it on...