I have been putting this off - I have been busy. Ruby 1.9 uses the YARV and seems to be about twice as fast as Ruby 1.8 - a nice speed improvement which is likely to get much better before a Ruby 2.0 release. I tried the new version on several of my POR (plain old Ruby) programs, and everything worked fine for me. Rails would not work for me, but I did not expect it to. I like the way that gem and rake are now bundled with Ruby 1.9 - that makes good sense.
With the good work also being done on JRuby and Rubinius, it is great to know that Ruby is under active development.