Changed field name, modified the User model, added unit tests.

app/models/user.rb

@@ -0,0 +1,5 @@
+class User < ActiveRecord::Base
+  def can?(action, page)
+    UserPagePermission.count(:conditions => ['user_id = ? AND page_id = ? AND action = ?', self.id, page.id, action.to_s]) > 0
+  end
+end

db/migrate/20110102045601_create_user_page_permissions.rb

@@ -3,7 +3,7 @@ def self.up
     create_table :user_page_permissions do |t|
       t.integer :user_id
       t.integer :page_id
-      t.string :permission
+      t.string :action
       t.timestamps
     end
   end

spec/models/user_spec.rb

@@ -0,0 +1,15 @@
+require File.dirname(__FILE__) + '/../spec_helper'
+
+describe User, 'permissions' do
+  before(:each) do
+    User.delete_observers
+    @user = User.create!
+    @page = Page.create!(:title => 'sample_title', :slug => 'sample_title', :breadcrumb => '...', :status => Status.find(1))
+    @user_page_permission = UserPagePermission.create!(:user_id => @user.id, :page_id => @page.id, :action => 'create')
+  end
+
+  it "should allow the user to create a page under the given page by a given user" do
+    @user.can?(:create, @page).should be_true
+    @user.can?(:destroy, @page).should be_false
+  end
+end