I'm wondering how one can use Bundler with Sinatra. The idea is to use the gems that Bundler downloads inside the .gems folder.
I believe the best way is described here on EngineYard blog:
# This makes sure the bundled gems are in our $LOAD_PATH
require File.expand_path(File.join(File.dirname(__FILE__), 'vendor', 'gems', 'environment'))
# This actually requires the bundled gems
Bundler.require_env
class MyApp < Sinatra::Base
# stuff
end