www.explainxkcd.com/wiki/index.php/1425:_Tasks

A month after this comic came out, Flickr responded with a prototype online tool to do something similar to what the comic describes, using its automated-tagging software. According to them, the bird solution “took us less than 5 years to build, though it’s definitely a hard problem, and we’ve still got room for improvement”.

(the site parkorbird.flickr.com is no longer online)