Expanding on a reply I just wrote to a comment on last night's Erlang post...
What Ruby and especially Rails did, though, is break IT free of the curly braces sociology. Used to be languages that did not resemble C would get skewed looks. When they'd receive attention they would be cast as odd-ball curiosities, far from viable in the mainstream.
Just think of all those Lisp and Smalltalk pieces in Dr. Dobbs and Byte over the years.
More generally than Ruby and Rails, I guess, is that the *web* did this. The web, being a large, dynamic system, demanded more than the traditional mainstream could supply, having been designed primarily for small, single-user systems that don't actually do all that much.