I wanted this ages ago for the N8x0.

IIRC, new versions of EOG do his for photos on the GNU/Linux desktop. I'd really prefer a solution that's independent from the maps-application on the N900 (or is configurable to use several map backends), so whatever we'll get in the end will still run on older models.


About people:
The problem with people is that to provide a good user experience, tagging should work for other peoples' photos as well. (And, of course, your tagged images should be recognized on my device should we have common contacts.)
Also, the solution must not break existing standards (which means we have to ask ourselves: where to put the information in EXIF/IPTC?)

Identifying people isn't a trivial task. In RDF-based solutions like FOAF we use either unique URIs or inverse functional properties. - URIs are ideal, but hardly useful for what we want to do here and now. There's something that FOAF uses, though, that we also find in our contacts: the email address. FOAF assumes that there are certain mail addresses that are unique to one person; these email addresses can be used to identify a person (or even a group of people).
My personal mail account is such an address. OTOH, if I enter office@acmecorp.com as my friend Lisa's address in the address book (because Lisa works at Acme Corp. and doesn't have internet at home), we run into problems... I might also know Lisa's best friend Sue, who also happens to work at Acme Corp. and doesn't have an account other than office@acmecorp.com.

In order to use the email address as an inverse functional property for identifying people, we should have a checkbox somewhere in an interface (for one of the applications used in the whole chain) that says: this mail address belongs to one person only, use it to identify this person.

The charming thing is that if we both know Rick, ad I tag a photo "rick@rainbowsarefree.com" and send it to you, it will integrate with your contact application as well.

(Other inverse functional properties used in the FOAF-universe, btw, are the homepage, the blog or an online account of a person. So while Lisa and Sue above share the same mail address in my address book, I might happen to know that each of that has a jabber-account of her own. I would choose Jabber instead of mail then in the interface, and it would still work for everybody who has complete contact data of Sue and Lisa.)

Don't get me started on all this or soon we'll have an RDF-based web of knowledge on our devices... (tracker already is RDF-based, isn't it? )