For people like me that use Gist or GitHub comments as a image hosting service like Imgur or the the now defunct ImageShack.
In due time (parts of) GitHub might become unavailable too, but since they diversified, I think the chance is lower. This is great because the list of List of image-sharing websites is not really growing but the subset of Defunct photo-sharing websites is.
You have to remember that unlike for instance Imgur, which can be used anonymously, the URL of pictures that are added to Gists or GitHub comments are bound to your GitHub user id.
So for instance [Wayback/Archive] 232005837-5d3c45d8-4efe-4759-a968-4ce276e35a35.png (899×503) contains the ID 2033367 which us the user ID of jpluimers.
The Wiert Corner - irregular stream of stuff 