600dpi should be enough for most printers, and, at a one-to-one viewing ratio, since screens are less than 100dpi, great for viewing.
With a digital camera (but not a cheap point-and-shoot), the resolution is many, many times higher. If you need to examine documents, or digitally repair old photos, higher is better. IF, of course, a camera is permitted.
With these glowing reviews, I'm going to have to try out a Flip-Pal!