I don't know how Maemo does it, but if done properly, there's a standard that says where/how to store

• GPS latitude/longitude/altitude/...
• state
• country
• city

All of this within the photo, not locally in some database.

There's, as far as I know, no standard that says "put the email address of the person on this photo in this field". however, one may want to look at the standards involved (mainly EXIF and IPTC) and see if there's fields that allow, say, entering private data or "additional information about the image" or whatever... then it's only a matter of making it clear that the address you find there was originally written by a Maemo device and is meant to identify a person as defined by the guidelines set by Maemo-application XY.