I want to rename an existing attribute's code to something else. The reason is because the attribute field is filled out for 300+ products and I don't want to have to re-import all of those just because I changed the code of an attribute.
It is much easier to use an upgrade script with the following content for that:
$installer = $this;
$installer->startSetup();
$installer->updateAttribute('catalog_product', 'old_attribute_code', array('attribute_code' => 'new_attribute_code'));
$installer->endSetup();