Flickr has launched their long-awaited feature Collections, which is sets of photosets. It’s been one of their most requested features for the last couple of years.
What are collections, you ask? A collection is a container into which you can place either sets or other collections, allowing you to create a hierarchy as deep as 5 collections. You can place as many of your sets into a collection as you like, and a set can be in as many different collections as you like.
They also added the ability to change the layout of your Flickr photos page.