I only played around with it a long time ago. Very interesting language indeed. You may also like Ioke (http://ioke.org/) - a jvm based language that is directly inspired by Io.
Ioke is lovely. Not particularly practical, but I had a ton of fun learning and contributing to it. More friendly and approachable and (if I understand Ola correctly) explicitly macro-friendly than Io. I think of it as the ultimate DSL language.
I've been looking for a post-lisp for some time now, and while I find Clojure very entertaining, RH took making it a Lisp seriously. This constrains it from the complete and utter evil I can accomplish with Io.
Also, fully translatable. Check out Hindi: http://github.com/olabini/ioke/blob/master/examples/multilan...