We’ve had a temporary storage failure affecting a sizable chunk of old Flickr photos and are moving about 20 terabytes of photos across a few thousand miles (between two of our data centers) to ensure consistency and smoothness. ALL PHOTOS AND DATA ARE SAFE AND NOTHING HAS BEEN LOST. The site will come back up as soon as possible.

In a few minutes we’ll make a decision about whether to bring the site back online right away, or wait until all the photos are sure to show up. (If we bring it up right away, there will be lots of "This photo is currently unavailable" images, but everything will function properly.)

UPDATE [4:59pm, pacific time (GMT-8)]: Weather report – everything is
still cool. We’re going to try to bring the site back online shortly
(there will still be photos which appear as unavailable, and they will
gradually fill in – no need to do anything on your part, dear user).

UPDATE 2 [5:52pm, pacific time (GMT-8)]: We’ve had some issues bringing
the site back online without this storage system but everything is
still quite safe and we are working hard to get back as soon as humanly
possible. One thousand apologies!

UPDATE 3 [7:58pm, pacific time (GMT-8)]: The site’s been back up for a while now, but I was on the freeway and couldn’t post. All’s well that ends well!