Paypal ipn forwarder / Gateway relay clarification

Hi !

The directory plugin comes with a "gateway relay" script, that seems similar to the ipn forwarder.

Where can we find docs on that ? Is it a ipn forwarder ?

This script is just essential for us multisites owners, that script should really be enhanced documented.

Why not having a little configuration file to simply use it and set it up on any server to be used with all commercial plugins using paypal that let us use one single ipn address to setup paypal gateways in several sites ?

Thanks for clarification, and sorry for that bad English message :s