Prints the root directory of the specified gem.
> gem dir -l rails
/Library/Ruby/Gems/1.8/gems/rails-2.3.4
Command line ninjas like myself can then do this, for example:
cd `gem dir -l memcache-client` && rake test
Just install like any normal gem: gem install gem_dir
You might need to install Gemcutter as a gem source: gem install gemcutter gem tumble
For more help: gem dir --help
Based on Adam Sanderson's sweet open_gem extension.