Imagine you live in a big town, in the pre-internet era. For years, a local newspaper has provided a neat service: it'll process your photos, so long as you let it publish them and keep the prints in its permanent archive.
Of course, most people throw away the negatives. But that's OK: the archive is right there.
Now, say you wake up one day and find that the newspaper's shutting down and has been keeping this fact pretty quiet. The archives will be destroyed. You're lucky to have found out at all! The proprietor ignores pleas to change course, and especially any offers to take possession of the set: to the furnace it will go. You call, and are assured they'll send you your prints, at least. But all that arrives in your mailbox is an empty envelope–or perhaps one containing a rag soaked in cat piss.
This is what's about to happen with twitpic, for years the go-to service for posting photos to Twitter, and the people in charge appear to be doing what they can to prevent the Internet Archive preserving the database and to deny users functional archive access to their own uploads.
"For this group of digital librarians," writes Pierre Chauvin, "saving a bunch of stranger's pictures is about keeping alive a key piece of our digital culture."