Oh, Folder Actions are wonnnnderful. Sorry to have been terse on the how-to aspect. (Have you seen my recipe for chicken pie? First you catch a chicken, then you bake it in a pie!)

Some resources and examples that will get you started:

http://www.tuaw.com/2009/03/26/applescript-exploring-the-power-of-folder-actions-part-iii/

http://dougscripts.com/itunes/itinfo/folderaction01.php

...The second one notes, "As of Snow Leopard (OS 10.6), Script Editor.app has been renamed AppleScript Editor.app and is located in your /Applications/Utilities/ folder." So, depending on what version of OS X you're using, now you know what you want to use and where to look for it.

Open that app up. Paste in the code from the post here. Save it. Easiest to just save it in your Documents folder, then drag it to ~/Library/Scripts/Folder Action Scripts ...OS X will ask for authentication if needed. Give that, and voila, your new script is now available to be attached to any folder.

So let's do that. Make a folder somewhere handy. Right-click on it. (On a Mac laptop, press the keypad with two fingers and click.) In the menu that pops up, scroll all the way down to Folder Actions Setup. In the box that pops up, click on the name of the script you just created. Click the Attach button. Done.

Now anytime you drag a file into that folder, it'll get processed by that script. Gad, it's a wonderful feature of OS X. Go crazy with it, you'll love it.