A lot of digital cameras store the metadata as EXIF. I could not find any CPAN modules mentioning EXIF, but there is a unix utility (called, quite originally, 'exif') which can read this data, and its output could easily be parsed.

You can check it out at http://sourceforge.net/projects/libexif

Update: as the previous poster mentioned, there's Image::Info, which actually does use EXIF for jpeg images.