About
Ruby is a nice, genuine object-oriented language, that comes from the the land of Rising Sun, Japan, where it is reportedly more popular than Python, to which it is often compared. It has recently been gaining momentum in the west. It is primarily developed on Linux, but also has a rather nice Windows version that includes; Ruby [obviously], SciTE [A pretty nice/simple IDE with support for Ruby], and Programming Ruby The Pragmatic Programmer's Guide.
Resources
Ruby-Talk [A English Ruby mailing list]
Learn To Program [A tutorial for the non-programmer using Ruby-- Must read, good place to start]
Programming Ruby [The Pragmatic Programmer's Guide, a good read after reading the above tutorial or good place to start if you already know quite a bit]
Examples
An example or two of ruby in action can be seen at RubyExamples.