Pretty awesome, yeah. XD It would actually make it less useful to me personally though, since my cheap web host doesn't support Ruby. >.>
Anyhow, I think Ruby's continuation support is a bit sketchy. There's no equivalent of Scheme's 'dynamic-wind built into the language as far as I know, so it may be necessary to use a patch like this one, which replaces callcc with a dynamic-wind-aware equivalent: https://github.com/mame/dynamicwind
Since there's no dynamic-wind, I haven't looked to see if there's a way to do continuation-friendly dynamic scope, like Racket's parameters. If that callcc replacement works though, it should be possible to implement parameters on top of Ruby, just maybe not that efficiently. :-p
Racket does a bunch of other interesting stuff with continuations, such as continuation marks, continuation guards, and... maybe that's it... and we'd lose those, but I think they're mainly useful for performance and well-specified 'letrec behavior, and who cares about that stuff? :-p
