gistfile1.rb

require 'rubygems'
require 'mongo_mapper'
require 'active_support'

ActiveSupport::CoreExtensions::Time::Conversions::DATE_FORMATS.merge!(
  :default => "%m/%d/%Y"
)

class Time
  def self.to_mongo(value)
    if value.nil? || value == ''
      nil
    else
      time = MongoMapper.time_class.parse(value.strftime('%a %b %d %H:%M:%S %Z %Y'))
      time && time.utc
    end
  end
end
MongoMapper.database = 'testing'



class Foo
  include MongoMapper::Document
  key :_id, ObjectId
  key :time, Time
end

Foo.collection.remove

Foo.create(:time => Time.now)

puts Foo.first.time.inspect