Well, #ruby 2.0 is shiny and all, but where're that refinements thing? Lets check. Searching google for example:

module TimeExtensions
  refine Fixnum do
    def minutes; self * 60; end
  end
end

class MyApp
  using TimeExtensions

  def initialize
    p 2.minutes
  end
end

MyApp.new    # => 120
p 2.minutes  # => NoMethodError

Installing ruby 2.0.0-p0 through rvm, ok.

Then, just trying to start example script:

$ ~/.rvm/rubies/ruby-2.0.0-p0/bin/ruby refinements.rb 
refinements.rb:2: warning: Refinements are experimental, and the behavior may change in future versions of Ruby!
refinements.rb:8:in `<class:MyApp>': undefined method `using' for MyApp:Class (NoMethodError)
    from refinements.rb:7:in `<main>'

Wait a minute, what means undefined method 'using'? Then refinement keyword's present but nothing works yet?

Sure thing nobody asked me to say that but I'm seriously pissed off.