I had a long discussion w/ Jason about that and I don't get why they specify it at all, other than to let people know that when the images are printed, they'll be tiny unless you render lots of pixels.

it's like you've commissioned a chef to cook for a banquet and have said, "we'll be serving rice in half-cup serving sizes," but neglecting to say how many people are attending the banquet.

when I asked about this, I was told that there is no minimum size for images.

also, after a bunch of back and forth, he said, "we want to avoid people submitting images at 72 ppi," but that's silly, IMHO - since he had said that he'd resize images if necessary.

when I've rendered images for print, I'd create a new file in Photoshop at the correct pixel size and the "resolution" set at 300.  then I'd open my render (most apps render out to computer-screen-viewable defaults of 72 pixels per inch, but that's another red herring as well), select all, copy, and paste it into my 'for print' document.

the whole ppi thing is a bit of a fiction.  it's a flag in the header of the digital image file that controls what the output device sees.  in Photoshop, for example, go into the Image Size dialog, make sure the "Resample Image" checkbox is NOT checked, and then change the 72 to a 300.  when this is done, the INCHES change, but the PIXELS remain the same!!

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