Yahoo recently started allowing its users to login with their Facebook accounts. Flickr, which is owned by Yahoo, has announced it will start letting users login with their Facebook account as well.
Once users have created a Flickr account using their Facebook credentials, they can visit their Flickr account settings to connect the two accounts via Yahoo Updates. This allows users to automatically share their Flickr activity to their Facebook feed, and use their Facebook profile picture as their Yahoo! public photo.
Since Flickr users can instantly share their links for their public photo uploads to Facebook, Flickr may see more referral traffic, but it may also see less direct visits since users won't have to check the website to see if friends have added new photos. Unfortunately, you cannot simultaneously post Flickr photos into your Facebook Photos albums, seeing as this would eliminate the need for the image hosting and video hosting website in the first place.