Rubinius runs Rails, Merb
Well, I’m super proud to say that tonight, rails served up both static and dynamic pages under Rubinius. Previous to tonight, we’d been blocked just trying to get Rails to even load. I decided to just try loading it up and bang on it enough to get it up and going.
To put this achievement in perspective: previously only Ruby 1.8.x and JRuby 1.x supported Rails. Other active Ruby implementations, such as IronRuby or the recently announced MagLev (built by Gemstone), are working towards this goal.
To be clear: there is still work left for the Rubinius team to fully support all Rails features and existing applications - but because Rails makes use of a lot of Ruby's features and behaviors, simply being able to launch Rails is seen as an important milestone for a Ruby implementation.
Wilson Bilkovich, also member of the Rubinius team, points out that ActiveRecord support is also starting to surface on Rubinius. Wilson also reports that Merb runs on Rubinius now. This comes a few months after Ruby Gems support was added to Rubinius (Merb requires Ruby Gems support).
You can check more of InfoQ's content about Rubinius - for the basics on Rubinius, check the interview with Evan Phoenix or the interview with Wilson Bilkovich.