my_awesome_spec.rb

require 'spec_helper'

describe "Registration" do
  
  before(:all) do
    FakeWeb.allow_net_connect = true
  end
  
  after(:all) do
    FakeWeb.allow_net_connect = false
  end
  
  it "should allow a user to register", :js => true do
    #tests here...
  end
  
end

selenium_fakeweb_workaround.rb

require 'selenium-webdriver'
class Selenium::WebDriver::Remote::Bridge
  
  def quit_with_fakeweb
    FakeWeb.allow_net_connect = true
    quit_without_fakeweb
  end
  alias_method_chain :quit, :fakeweb
  
end