Can confirm that those high dpi numbers are real. (I paid for my last year in college rendering film for offset press on a 25'x6'x6' monster scitex film printer).
Although the plate or film is rendered at 1600/2400/3200/4800 dpi, the dot gain from the ink soaking into the paper tends to blur fine details. The printing software tried to account for the dot gain, but it was still there.
If you look at a 300dpi laser printer output vs 600dpi, most everyone can tell if they look. Higher resolutions may need a loupe to discern differences.
