Start Me Up: Writing and Understanding OS X StartupItems
Subject:   StartupItems may soon be moot
Date:   2005-03-08 18:28:05
From:   ylon
Response to: StartupItems may soon be moot

From the looks of it StartupItems will probably not be going away too soon, plus I've read:
"The documentation fails to mention this, but this facility is for Mach Servers only, and there is no replacement for SystemStarter available."

Now whether that is still true, I know not.