Uhm---yes, it should run in Automator and no, it doesn't. It must be that it doesn't know what to run on. The only input actions in the list that look remotely appropriate are Get Selected Finder Items and Get Specified Finder Items. I didn't see anything that would look for something new in a folder---or allow me to somehow designate what's new. It's important that it be able to find a new item, since I can't tell it a file name, as new items will come in named with the time of creation.

I will definitely do it! Thanks for the tutorial references, and mucho thanks for your time on this. If you have any sudden flashes of insight, call collect... http://processing.org/discourse/yabb2/yabbfiles/Templates/Forum/processing_one/smiley.gif

Update on automatic printing of a PDF saved from a running Processing animation:

First, thanks to Scott M. for getting me very close. Second, it's working! Here's what I did:
The key is to start with Automator (Mac OS X). In Automator, from the list under Library, select Photos. From the Photos list, select Print Images and drag it to the space on the right where you build workflows. It turns out that this is all you need, so save it with Save as Plug-In." In the drop-down window, name your new script, select Folder Actions where it says Plug-In for:, and then put in the name of the folder where you want this to happen where it says Attached to Folder:. Make sure that Folder Actions are enabled on that folder (see Scott's directions above), and you're set. The script will do it's thing (in this case, printing) on the next new file to be added to that folder, whatever it's name. You don't have to explicitly identify the new file for the script to work.