Some further modifications in the files 
mentioned here were necessary to get the initial setup runable.
(System configuration: WinXP, JRuby 1.5.1, CouchDB 0.11, couchapp 0.6.2)
- step_definitions/common_culerity_steps.rb - add this
 - def couchapp 
-   'rem' # enter your couchapp name here 
- end 
 
-  support/paths.rb - modify 
 
 Before:
 -     when /start page/                                             
-       "/#{database}/_design/#{database}/index.html" 
-     else                                                          
-   
 
 -     when /start page/ 
-       "/#{database}/_design/#{couchapp}/index.html" 
-     else 
 
- step_definitions/common_culerity_steps.rb - remove ":resynchronize => true," from
 -     $browser = Culerity::RemoteBrowserProxy.new $server, { 
-       :browser => :firefox,  
-       :javascript_exceptions => true,  
-       :resynchronize => true,  
-       :status_code_exceptions => true} 
-   
 
- start_page.feature - modify the example scenario to
 -   Scenario: go to the start page          
-     When I go to the start page           
-     Then I should see the text "Generated CouchApp" 
 
After this modifications I got:
E:\projects\privat\rem>jruby -S cucumber --no-color
Feature: start page
  In order to feel welcome
  As a user
  I want to be welcomed on the start page
  Scenario: go to the start page                    # features\start_page.feature:7
2010-07-10 17:01:12 [INFO] Visit your CouchApp here:
http://localhost:5984/hejhej/_design/rem/index.html
    When I go to the start page                     # features/step_definitions/common_culerity_steps.rb:90
    Then I should see the text "Generated CouchApp" # features/step_definitions/common_culerity_steps.rb:119
1 scenario (1 passed)
2 steps (2 passed)
0m8.625s
E:\projects\privat\rem>