Magento – How to Get Product IDs from $observer->getEvent()->getOrder()

The problem is, that you are not allowed to save products from the frontend.

This is done through the fact, that when you load a product in frontend, the origData property is not filled:

public function setOrigData($key=null, $data=null)
{
    if (Mage::app()->getStore()->isAdmin()) {
        return parent::setOrigData($key, $data);
    }

    return $this;
}

So when you try to save the product, the error you describe is raised.

You can solve this problem either when you change the current store to admin, e.g. with the code from @magboy:

Mage::app()->setCurrentStore(Mage_Core_Model_App::ADMIN_STORE_ID);

better using Mage_Core_Model_App_Emulation

And my prefered solution is to extend Mage_Catalog_Model_Product and replace the setOrigData method

public function setOrigData($key = null, $data = null)
{
    if (is_null($key)) {
        $this->_origData = $this->_data;
    } else {
        $this->_origData[$key] = $data;
    }
    return $this;
}

I'm NOT talking about a rewrite here! Only use your model on this one place to enable saving. Then you have the security-feature still active everywhere else.

The observer receives as a parameter the order (or orders for multishipping) and the quote. Here is how you can get them

public function galileo_booking_request(Varien_Event_Observer $observer) {
    $order = $observer->getEvent()->getOrder(); //I don't know why this returns null for you. It shouldn't
    //or for multishipping
    //$order = $observer->getEvent()->getOrders(); //you should get an array of orders
    //for the quote
    $quote = $observer->getEvent()->getQuote();
}

If it doesn't work for you for the order, try with the quote. After getting the quote object your can loop through the items.

foreach ($quote->getAllItems() as $item) {
    $product = $item->getProduct();//if you need it
    //your magic here.
}