reading the comments in this thread reminds me why i rarely read comments on slashdot.
mirah is java, with a friendlier type system and ruby-like syntax. like jruby, but without having to drag around a huge runtime library, or maintain language compatibility with a language with no spec (ruby).
mirah compiles directly to bytecode, just like java, so it's as fast as java. it has type inference, so types are still there if you want/need them. the syntax is a matter of religion and/or taste, i tend to like it. you also get the entire corpus of java frameworks and libraries for free.
i personally am _more_ excited about mirah than i am about jruby (or even ruby for that matter).
charles nutter is one of the main (the main?) guy behind jruby for those who (for some reason) think this is some sort of attack on jruby.