It's probably better practice anyway to have one script running under the uid you want to set to as a listener/server/daemon/whatever and having information passed to it by the script running under the original uid. Of course there is a multitude of ways you can do this. *nix is nice in that you can use fifos, but sockets are also fun :). On the other hand I suppose you could use files and perhaps Data::Dumper - the possibilities are endless.

It's what I've been doing and it works fine.