Interestingness and clustering (Stewart Butterfield: 'It's easier to show than to tell, so here are some examples: love, terror, nose, bush, cameraphone'), two new developments at Flickr:
Both interestingness and clustering rely a lot on what people are doing, whether it's with the photos they like, or the tags they are using. You can think about it as people-powered searching. Yahoo! Search Blog
Of clustering, Cory says it's 'a major improvement to Flickr's "tagging" feature, whose main failing to date has been the ambiguity in tags -- some people tag photos of bushes with "bush," others tag pictures of the President with "bush." Clustering to the rescue -- it automatically finds the congruences in tags and groups them according to the discovered relationships'.
Interestingness (= photorank) is throwing up some wonderful photographs.
There are lots of things that make a photo 'interesting' (or not) in the Flickr. Where the clickthroughs are coming from; who comments on it and when; who marks it as a favorite; its tags and many more things which are constantly changing. Interestingness changes over time, as more and more fantastic photos and stories are added to Flickr. Flickr
A long time in the making, interestingness is a ranking algorithm based on user behavior around the photos taking into account some obvious things like how many users add the photo to their favorites and some subtle things like the relationship between the person who uploaded the photo and the people who are commenting (plus a whole bunch of secret sauce). Flickr Blog
The Flickr Explore page is a great front end for keeping users up to date with developments.

