And how is the Internet celebrating? So many ways: The Huffington Post got Sinead O’Connor to write a love letter for “Zimmyâ€; the AV Club rounded up “some of the weird shit he’s done†(Soy Bomb guy, it’s been too long); BBC News uncovers an old, heroin-addiction-revealing interview; and Rolling Stone swags it out with a whole best-of-Dylan package. Vulture is marking the occasion, tangentially, with “One Headlight†on repeat. How are you celebrating?