[aplaice]

It's rather sad that none of the images (that I checked — I might be wrong) on blog.mozilla.org seem to have an alttext.

(For the record, while I generally dislike gifs, I don't have strong feelings, either way, regarding the animated image here.)

[Bartweiss]

That is unfortunate. I'm not generally opposed to sensible use of images or (occasionally) gifs, but the practice of describing their contents in alttext is excellent - it enables both usability and machine-readability, and I really hope it catches on more widely.