rubygems.rb

%w{merb-core merb-haml syntax}.each do |gem|
  gem_package gem 
end

# Upgrade
%w{merb-core merb-haml syntax}.each do |gem|
  gem_package gem do
    action :upgrade
  end
end

# Upgrade to version
%w{merb-core merb-haml syntax}.each do |gem|
  gem_package gem do
    version '1.0.8.1'
    action :install
  end
end