How do I script converting a .psd or .ai file into multiple sized PNGs?

For iPhone programming, I need my application icon in many sizes.

Rather than have my designer export one by one, is there a way I can script photoshop, illustrator, or just use Python or some开发者_如何学JAVAthing to convert a .PSD or .AI file into several different sizes of .PNG?

My best guess would be to create an action in Photosop (sort of making a Macro) and doing a batch in the File -> Automate -> Batch option.

Check this link out for more info (Mac based tutorial but i've done it in the PC version).