Delaying the server response...

Hello everyone,
    I read in the docs that you can delay the server response by passing
a second parameter of "0" to the xmlrpc_server function.  At this point
in the process, what information about the client is available for
things such as authentication?  Remote host?  And how can they be
accessed (through typical php means?)?  A quick example would be greatly
appreciated.

Thanks.

j