I understand the kids are into this whole "social media" thing, which is why I ask. It might catch on.
The easy way to accomplish this would be to just upload every photo I add to the web site's gallery to a gallery on Facebook as well, but that kind of duplication really rubs me the wrong way. Also, then there are two URLs for each gallery, and which one do I link to? The "real" one, or the one where you can tag yourself and your friends? Making bidirectional links between the photos on the two sites might be possible, but it would be a whole lot of work.
The DNA galleries have been around since long before Facebook existed and I fully expect them to outlive it as well, so obviously "post them to Facebook but not the DNA site" is not on the table.
Flickr has similar functionality, and while all you said about facebook applies to flickr, too, it may be possible to find out from the flickr folks how they manage tagging. (You might be able to ask folks at facebook, too, but I 'd suggest waiting until you're done with the ABC and the building department - you don't need additional threats to your sanity.)
Could you just allow them to individually "like" or even "attend" the photos? They probably don't need (in most cases) to point out exactly where in the photo they are.
I think it may be possible without needing to upload the images to Facebook, but you'll have to make your own Facebook Web App for it, or build into an existing one.
The key is to treat each photo as a Open Graph object, then assigning the tags can be done per user. Since each photo has it's own unique URL, you're most of the way there. Users who want to tag themselves on a photo on your site would need to accept permissions to that Facebook app the first time, then can tag from there. You should be able to display people tags who set their permissions to public for in-line display.
Here's a few docs that talk about the various things you want to do. Hopefully this can be a good starting point.
* Mention Tagging
* User Generated Photos
* Location Tagging
The Rental Car Rally guys took the "build your own app" approach for their "Past Rallies" stuff - http://www.rentalcarrally.com/rallies/past -- it's possible to comment on some things there (maybe just team pages, but I thought pictures as well), but the images actually reside on S3. Looking again just now, though, I don't see any way to tag the images… which doesn't mean it's impossible to do that, just that Yutai didn't.
A true FB gallery is most likely to get the user laid: If she flubs her opportunity to connect in-person, she's got another chance when she gets tagged in the same shot as him.
I thought FB had some sort of facial recognition feature.
And how does this apply to what JWZ is asking?