Magento: Activate products in the future

gistfile1.php

<?php
/*
Follow these steps to create this functionality:
1. Create a custom date attribute, lets call it ‘activation_date’
2. Create a cron job that should implement the following:
2.1 Retrieve all product ids that were not activated (E.G. status disabled) and their activation date
    is lower than current date
2.2 Activate all these products by the product attribute mass-action model:
*/

Mage::getSingleton('catalog/product_action')
    ->updateAttributes(
        $retrievedProductIdsArray,
        array('status' => Mage_Catalog_Model_Product_Status::STATUS_ENABLED),
        Mage_Core_Model_App::ADMIN_STORE_ID
    );

/*
3. Schedule the cron job in your module configuration file (config.xml) 4. Enjoy It!
*/