Mage::app()->getStore()->getWebsiteId(); does not work in some blocks, (called from an instatianted Model).
If I remember correctly, it works in the cart block, but does not work in the cart Items block.
I thought it was an intersting problem. I also noticed that Mage::getModel('customer/session')->getCustomer()->getGroupId();
also doesnt work in the same situation.
It works from within a template in a block called: Mage_Checkout_Block_Cart
But it doesnt work from within a block called: OrganicInternet_SimpleConfigurableProducts_Checkout_Block_Cart_Item_Renderer which extends Mage_Checkout_Block_Cart_Item_Renderer
Any thoughts?