Pretty graphs here: http://www.isrubyfastyet.com/ (I run a nightly benchmark.)
I will add 2.1.0 right now and hopefully we will have confirmed data in the morning.
EDIT: You mention 20% improvement on Rake tasks. Simple Rake tasks are dominated by Rails' startup time. My benchmark reads about a 15% improvement in startup time, which agrees with what you are saying.
However, the 1.9 series was a significant step back from 1.8.7 for out-of-the-box Rails startup time. Ruby 2.0.0 pretty much matched Ruby 1.8.7. Now with 2.1.0, Ruby is finally categorically faster than 1.8.7 for starting Rails. (Rails itself has also made improvements; but my benchmark has been locked at Rails 3.1.3)