When I first posted the link, I was missing the "RunAtLoad" key which requests that service to run when launchd loads the config file. Stefan Schumacher pointed this out to me, and it is corrected now.
cheers,
ben
I was accustomed to running postfix as a service under 10.2 and 10.3.
I've written up a page on how to do it under launchd in 10.4 (tiger). It isn't difficult.
The page is here: http://http.modulo.org/code/tiger-postfix.html
cheers,
ben