gistfile1.rb

# ACTIVATIONS_CONTROLLER.RB
class ActivationsController < ApplicationController
  before_filter :require_no_user, :only => [:new, :create]
  before_filter :load_and_verify_user, :only => [:new, :create]

  def new
    render
  end

  def create
    @user.assign_credentials!(params) unless params[:user].nil?
    @user.activate!
    @user.save do |result|
      if result
        @user.deliver_perishable_email!(:activation_confirmation)
        flash[:notice] = "Your account has been activated."
        redirect_to admin_user_path(@user)
      else
        render :action => :new
      end
    end
  end

  private
  
  def load_and_verify_user
    @user = User.find_using_perishable_token(params[:activation_code], 1.week)
    logger.info ">>>>> LOAD #{session.inspect}"
    if @user.nil? || @user.confirmed?
      flash[:error] = "We could not locate your account."
      redirect_to root_path and return
    end
  end

end

gistfile2.rb

# USER.RB
class User < ActiveRecord::Base
  attr_accessible :email, :password, :password_confirmation, :openid_identifier
  
  # AUTHLOGIC
  acts_as_authentic do |u|
    u.validates_length_of_password_field_options = validates_length_of_password_field_options.merge({ :on => :update })
  end
  
  # NAMED SCOPES
  named_scope :active, :conditions => { :active => true }
  named_scope :inactive, :conditions => { :active => false }
  named_scope :by_created_at, :order => "created_at DESC"
  
  # CALLBACKS
  after_create :deliver_activation_instructions!
  
  def signup!(params)
    self.email = params[:user][:email]
    save
  end

  def assign_credentials!(params)
    self.password = params[:user][:password]
    self.password_confirmation = params[:user][:password_confirmation]
    self.openid_identifier = params[:user][:openid_identifier]
  end
  
  def activate!
    self.active = true
    self.confirmed = true
  end

  # Email notifications
  def deliver_perishable_email!(email)
    reset_perishable_token!
    Notifier.send("deliver_#{email}".to_sym, self)
  end
  
  def deliver_activation_instructions!
    self.deliver_perishable_email!(:activation_instructions)
  end
  
  # Helper methods
  def active?
    active == true
  end

end