common.rubygems

~/Code/rubygems /master > gem list gemcutter

*** LOCAL GEMS ***

gemcutter (0.6.1, 0.5.0)
~/Code/rubygems /master > irb -rubygems
ruby-1.8.7-p299 > Gem.find_files "rubygems_plugin"
 => ["/Users/wycats/.rvm/gems/ruby-1.8.7-p299/gems/gem-open-0.1.2/lib/rubygems_plugin.rb", "/Users/wycats/.rvm/gems/ruby-1.8.7-p299/gems/gemcutter-0.5.0/lib/rubygems_plugin.rb", "/Users/wycats/.rvm/gems/ruby-1.8.7-p299/gems/gemcutter-0.6.1/lib/rubygems_plugin.rb"] 
ruby-1.8.7-p299 > Gem.loaded_specs.map {|k,v| v.full_name }
 => ["gem-open-0.1.2", "gemcutter-0.5.0", "json_pure-1.4.6"] 
ruby-1.8.7-p299 > exit
~/Code/rubygems /master > gem uninstall gemcutter

Select gem to uninstall:
 1. gemcutter-0.5.0
 2. gemcutter-0.6.1
 3. All versions
> 1
Successfully uninstalled gemcutter-0.5.0
~/Code/rubygems /master > irb -rubygems          
ruby-1.8.7-p299 > Gem.find_files "rubygems_plugin"
 => ["/Users/wycats/.rvm/gems/ruby-1.8.7-p299/gems/gem-open-0.1.2/lib/rubygems_plugin.rb", "/Users/wycats/.rvm/gems/ruby-1.8.7-p299/gems/gemcutter-0.6.1/lib/rubygems_plugin.rb"] 
ruby-1.8.7-p299 > Gem.loaded_specs.map {|k,v| v.full_name }
 => ["gem-open-0.1.2"] 
ruby-1.8.7-p299 >