Yet another reason why I’d wish OpenID to take off and being applied by some big players:
From: FlickrHQ
…
On March 15th we’ll be discontinuing the old email-based Flickr sign in system. From that point on, everyone will have to use a Yahoo! ID to sign in to Flickr.
…
So, until 15th of March I have to get a Yahoo! ID in order to use my (paid) Flickr account any longer. I hardly can keep track of my existing registrations and tons of user accounts across the internet already.