well, olympus does this as well in the exif tags (they have sensor temperature and lens temperature in there somewhere, in dedicated tags).
well, i for one wouldnt be unhappy if it was added in the usercomment, because that field is a) empty as of now and b) every application reads that as default and c) we *could* extend this later with more stuff, or even maybe the user decides what non-standard info (like temperature, overrides etc) he would like to see in that usercomment, by the use of checkboxes). i dont know how hard it would be to add this, i tried once, but adding non-fixed values i couldnt achieve.
