I shoot with a Nikon D40x and organize and process my photos using iPhoto '08 (I have Lightroom, but haven't spent much time with it yet). I noticed that when I edit images using iPhoto, the changes are not made to the original file, but to a jpeg that iPhoto creates from the original. While the resolution remains the same, the copy is always 72 dpi. Again, the total pixel count is the same (3800 x 2600). So, does it matter what the jpeg dpi is? Does it have any relevance at all?