For the most part, we've been pretty good about keeping JRuby 
discussions off the ruby-talk list, because in general it seemed like 
the right thing to do. But lately, it seems like people are missing 
information about what JRuby can do, how complete the implementation is, 
and where we're going with it. So I'd like to start talking more about 
JRuby on this mailing list.

I'll start it off with a little introduction to JRuby and what it can do 
right now.

JRuby is Ruby for the JVM, also known as the Java Virtual Machine. It's 
written mostly in Java, though there's some libraries written in Ruby, 
and we include the entire Ruby 1.8.x (currently 1.8.5) stdlib.

In the 1.0 line, JRuby operates primarily as an interpreter comparable 
to the standard Ruby 1.8.x implementation.

In 1.1, JRuby includes a 100% complete Ruby-to-bytecode compiler, that 
increases performance substantially.

JRuby runs Rake, RubyGems, Rails, Mongrel, and nearly all pure-Ruby 
libraries and apps that are out there. Compatibility has gotten closer 
and closer to 100% over the past year.

There are a number of organizations rolling out real production Rails 
apps on JRuby rather than on regular Ruby, usually because JRuby fits 
better into Java-oriented organizations, but increasingly because JRuby 
offers libraries, stability, and performance characteristics in many 
ways better than running on the standard implementation. It's not better 
across the board, but it's starting to be better in very important areas.

JRuby 1.0.1 is the current release. 1.0.2 is going to be released within 
the next two weeks, along with a beta of 1.1.

What more would folks like to know about?

- Charlie