I’ve just released a very early version of a bridge that allows Rails applications to run reports written by the java reporting tool DataVision.
DataVision supports ruby as a scripting language (via JRuby) so it seemed a good fit. I haven’t had a chance to get my head around releasing it as a gem, plugin, etc so right now it’s just a tar that you extract in the directory of the app you want to "reportify".
You can download and/or find out more at rdb.rubyforge.org
Enjoy!