rubygems - Image Not Found Errors after Upgrade to Rails 3.1, how to fix?

Question

I'm getting this warning everytime I load my rails server after I upgraded to rails 3.1 from rails 3.0. Not sure what it is. I've tried reinstalling everything from rvm and ruby to all my gems. My guess is some gem is not supported in rails 3.1 but I can't seem to find which one or for some reason I don't have the dependencies installed for a specific gem.

Could not open library 'libgtk-x11-2.0': dlopen(libgtk-x11-2.0, 13): image not found.
Could not open library 'libgtk-x11-2.0.dylib': dlopen(libgtk-x11-2.0.dylib, 13): image not found.
Could not open library 'libgtk-x11-2.0.so.0': dlopen(libgtk-x11-2.0.so.0, 13): image not found.
Could not open library 'libgtk-x11-2.0.so.0.dylib': dlopen(libgtk-x11-2.0.so.0.dylib, 13): image not found.
Could not open library 'libgtk-x11-2.0.so': dlopen(libgtk-x11-2.0.so, 13): image not found.
Could not open library 'libgtk-x11-2.0.so.dylib': dlopen(libgtk-x11-2.0.so.dylib, 13): image not found.
Could not open library 'libgtk-3': dlopen(libgtk-3, 13): image not found.
Could not open library 'libgtk-3.dylib': dlopen(libgtk-3.dylib, 13): image not found.
Could not open library 'libgtk-3.so.0': dlopen(libgtk-3.so.0, 13): image not found.
Could not open library 'libgtk-3.so.0.dylib': dlopen(libgtk-3.so.0.dylib, 13): image not found.
Could not open library 'libgtk-3.so': dlopen(libgtk-3.so, 13): image not found.
Could not open library 'libgtk-3.so.dylib': dlopen(libgtk-3.so.dylib, 13): image not found

Answer 1

This comes from using the libnotify gem on OSX. You can circumvent this by specifying the OS in your Gemfile like so:

gem 'libnotify' if /linux/ =~ RUBY_PLATFORM
gem 'growl' if /darwin/ =~ RUBY_PLATFORM