Following the Harry Potter story, EXIF stores even more personal information than I first thought in images – as you’d expect Wikipedia has all the details. The camera serial number is the obvious personal information you might want to remove, but date and time are stored which could be tricky. And cameras with GPS capability can store the location the photo was taken as well. Scary!
One of the least obvious but perhaps potentially most embarrassing aspects, though, is that if you edit a photo, the EXIF data may still contain a thumbnail of the original photo. Can you guess where this is leading? Yes, a certain Cat Schwartz (who’s apparently a minor celebrity in some circles) posted cropped photos of herself on her blog, and the EXIF data contained thumbnails of the original, uncropped photos that showed her posing topless. Full story here (but the links to Schwartz’s blog and the photos are now dead).