It’s not just because flickr popularized them that I like them, though it helps and you should definitely look at that stuff:
- The announcement
- Excitement from O’Reilly Radar, ProgrammableWeb, and Dan Catt (who championed the concept at flickr, I think).
Part of what I like about machine tags is that they bring some more structure (but not too much) to the folksonomic ecosystem. I’m not sure how many of the 292 named flickr mashups use machine tags, but there’s a lot of possibility in them.