Its for automating certain tasks, eg. make an automater script to check a folder and upload all new images to a certain location. Its basically a GUI for Applescript.
then its quite useless. I'm hoping that linked site becomes more popular, as I hear automator has a lot of useful things for people who repeat tasks a lot.
Startup routines would be cool if it could do them. I can imagine setting up the thing to open specific programs, place certain windows at certain locations, and do several other routine tasks that I do at startup.