This is especially common in data warehouses, as the dimension tables need to be populated with all of the attributes that a user will be searching/drilling on

This is especially common in data warehouses, as the dimension tables need to be populated with all of the attributes that a user will be searching/drilling on (including dates). I don't think I've ever come across a transactional system with a dedicated date table -- you usually have access to a good suite of date-manipulation operations in SQL -- but maybe there's a case for it.