straup from Flickr recently posted about a new tagging feature in Flickr called Machine Tags:

We are rolling out a new feature called “machine tags” that allows users to be more precise in how they tag, and how they search, their photos.

- When a user tags an event with an upcoming ID (for example : “upcoming:event=81334”) we display a link back to the upcoming.org site.

We’ve thought about this idea in SWiK, and I’ve seen something similar on another Yahoo property: del.icio.us with system:filetype:jpg tags that I use to power delimages.

I wonder if it would be too crazy to formalize machine tagging and give it domain namespaces?

For example, if you tag a bookmark on del.icio.us “upcoming.org:event=foocamp”, del.icio.us could run off to upcoming.org and grab some info about foocamp.

Another advantage to machine tags is giving you search access and combination opportunities to locked up system metadata. GMail has a good example of this: if you want to find emails from Alex in gmail, you can search using “From:alex”. There’s a laundry list of these Machine Tags on gmail.

Google of course has the luxury of making every word in your gmail a tag that describes it, but they also add these system tags to add power above that.

Adding domain specific tags could help in gmail too. Making a label in gmail called “upcoming.org:event=foocamp”, tagging emails with that label, and then having Google Calendar remind me on the date of Foocamp all the emails I tagged as related to the event.