I'm just curious, because there's really two ways it could be looked at... 1) images are almost never used (minus the google images search- but that's a different case entirely). even on the cached page, it still tries to get the images from the actual site. the images aren't needed in most cases, so downloading them would just be a waste of time (and bandwidth) for the bot... however 2) by downloading the images, it could look for abuse (ie transparant gifs with hyperlinks) so I'm just wondering, does google request image files normally?
THey do for the image search, but that's really the only time. And it's so rare is silly... images are usually like a year out of date.