Avoiding the undefined method `use_transactional_fixtures=' error. After adding rspec to my project and generating a model with rspec_model, I tried to run the generated spec test: 
$ spec -cfprofile spec/
.../toshi/spec/spec_helper.rb:12: undefined method `use_transactional_fixtures=' for # (NoMethodError)
 from /usr/lib/ruby/gems/1.8/gems/rspec-1.1.11/lib/spec/runner.rb:184:in `configure'
 from /home/medined/Workspaces/toshi/spec/spec_helper.rb:8
 from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
 from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:31:in `require'
 from /home/medined/Workspaces/toshi/spec/models/book_spec.rb:1
After a fruitless internet search, I tried using a rake task: 
$ rake spec
.
Finished in 0.061996 seconds
1 example, 0 failures