query cache about the federated engine

[wangxu]

    I have a problem about the performance of federated engine. The mysql5.0 
reference manual says that the FEDERATED tables do not work with the query 
cache, aren't they? How about the query cache used by the federated engine in 
the mysql5.1? 
    If the query cache cann't be used with the federated engine tables still, 
how to enhance the query performance against to the federated tables 
effectively?