Absolutely, but contrasted with say 'logo' the power of ruby is that it is not a 'toy' language, you can build just about anything other than hard real time systems in it.

That's a pretty powerful tool to master. The only other languages that I can think of that are that accessible to children are Logo, Basic and SmallTalk and none of those is as well established as a starting language for kids to use and as powerful at the same time.

The lego robotics kits are nice and well thought out but there is no stepping stone between there and say making a website or some other non lego-related program.

Robots and turtles are cool in that they allow control of real-world objects from a programming environment.