I wonder if they'll do one about deployment too (like Capistrano, Passenger, etc). I heard they used to use Capistrano, REE, and Phusion Passenger but have been moving to Ruby 1.9.2 and Unicorn but it'd be interesting to hear more.

In terms of test framework, however, the answer is well known ;-) http://www.rubyinside.com/dhh-offended-by-rspec-debate-4610....