Wrong website assignment for tier prices if price scope is set to Global.
If price have global scope then tier price website_id must always set to 0.
(Creating tier price In Magento AdminPanel has the same behaviour).
Otherwise tier prices will not shown in product view (Admin and Frontend).
If price is in website scope, we can use website values.
See AdminPanel: System - Configuration - Catalog/Catalog - Price - Catalog Price Scope
Attached file is based on version 0.0.7a.
I tested this Patch in Magento Version 1.6.2 only, but i think it must also work in other versions, because tables and configuration values are same.