Well these appraisal gemfiles changed by running appraisal.

gemfiles/rails2.gemfile

 # This file was generated by Appraisal
 
 source "http://rubygems.org"
-gem "shoulda"
-gem "mocha"
+
+gem "rails", "~>2.3.0"
 gem "rake"
-# gem "ruby-debug", {:platform=>:ruby_18}
-# gem "ruby-debug19", {:platform=>:ruby_19}
-gem "aws-s3", {:require=>"aws/s3"}
 gem "sqlite3-ruby", "~>1.3.0"
-gem "appraisal"
-gem "fog"
-gem "bundler"
 gem "cocaine"
-gem "rails", "~>2.3.0"
+gem "shoulda"
+gem "mime-types"
+gem "mocha"
+gem "bundler"
+gem "fog"
+gem "aws-s3", :require=>"aws/s3"
+gem "appraisal"
+gem "rdoc", :require=>false
+

gemfiles/rails2.gemfile.lock

@@ -46,6 +46,7 @@ GEM
       activesupport (= 2.3.10)
       rake (>= 0.8.3)
     rake (0.8.7)
+    rdoc (3.8)
     ruby-hmac (0.4.0)
     shoulda (2.11.3)
     sqlite3-ruby (1.3.2)
@@ -60,8 +61,10 @@ DEPENDENCIES
   bundler
   cocaine
   fog
+  mime-types
   mocha
   rails (~> 2.3.0)
   rake
+  rdoc
   shoulda
   sqlite3-ruby (~> 1.3.0)

gemfiles/rails3.gemfile

 # This file was generated by Appraisal
 
 source "http://rubygems.org"
-gem "shoulda"
-gem "mocha"
+
+gem "rails", "~>3.0.0"
 gem "rake"
-# gem "ruby-debug", {:platform=>:ruby_18}
-# gem "ruby-debug19", {:platform=>:ruby_19}
-gem "aws-s3", {:require=>"aws/s3"}
 gem "sqlite3-ruby", "~>1.3.0"
-gem "appraisal"
-gem "fog"
-gem "bundler"
 gem "cocaine"
-gem "rails", "~>3.0.0"
+gem "shoulda"
+gem "mime-types"
+gem "mocha"
+gem "bundler"
+gem "fog"
+gem "aws-s3", :require=>"aws/s3"
+gem "appraisal"
+gem "rdoc", :require=>false
+

gemfiles/rails3.gemfile.lock

@@ -83,6 +83,7 @@ GEM
       rake (>= 0.8.7)
       thor (~> 0.14.4)
     rake (0.8.7)
+    rdoc (3.8)
     ruby-hmac (0.4.0)
     shoulda (2.11.3)
     sqlite3-ruby (1.3.2)
@@ -101,8 +102,10 @@ DEPENDENCIES
   bundler
   cocaine
   fog
+  mime-types
   mocha
   rails (~> 3.0.0)
   rake
+  rdoc
   shoulda
   sqlite3-ruby (~> 1.3.0)

gemfiles/rails3_1.gemfile

 # This file was generated by Appraisal
 
 source "http://rubygems.org"
-gem "shoulda"
-gem "mocha"
+
+gem "rails", "~>3.1.0.rc1"
 gem "rake"
-# gem "ruby-debug", {:platform=>:ruby_18}
-# gem "ruby-debug19", {:platform=>:ruby_19}
-gem "aws-s3", {:require=>"aws/s3"}
 gem "sqlite3-ruby", "~>1.3.0"
-gem "appraisal"
-gem "fog"
-gem "bundler"
 gem "cocaine"
-gem "rails", "~>3.1.0.rc1"
+gem "shoulda"
+gem "mime-types"
+gem "mocha"
+gem "bundler"
+gem "fog"
+gem "aws-s3", :require=>"aws/s3"
+gem "appraisal"
+gem "rdoc", :require=>false
+

gemfiles/rails3_1.gemfile.lock

@@ -91,6 +91,7 @@ GEM
       rake (>= 0.8.7)
       thor (~> 0.14.6)
     rake (0.9.0)
+    rdoc (3.8)
     ruby-hmac (0.4.0)
     shoulda (2.11.3)
     sprockets (2.0.0.beta.8)
@@ -116,8 +117,10 @@ DEPENDENCIES
   bundler
   cocaine
   fog
+  mime-types
   mocha
   rails (~> 3.1.0.rc1)
   rake
+  rdoc
   shoulda
   sqlite3-ruby (~> 1.3.0)