The ruby issue should improve performance of rails 3.0 as well. Given that the parent was comparing two rails versions on the same ruby version, I do think there has been a degradation in rails itself.
His solution is to break up the pipeline into 3 separate types: generators, filters (for response data), and lifecycle hooks. Doing this brought the speed back up to rails 2.3 speeds and a bit faster in some instances. But those were early numbers.
You can see his talk here: http://www.youtube.com/watch?v=kWOAHIpmLAI
The interesting stuff happens around the 20 min. mark.
Overall, there are a lot of people who want to make ruby better and faster. Rubinius, Jruby and MacRuby are all examples. There are also people who want to make Rails faster. They are examining the slower parts (active record, rack, etc) and working to make it better.