Yesterday, at a signing at JordanCon, Brandon read out something that was very old, which he said we had been waiting for "for a long time". He thought it was about eight or nine years old. It is crazy, and very exciting. It's a piece called The Traveler which is quite cosmere-aware, which Brandon thought he could now reveal. We recommend you just read it with no further introduction, but if you want some analysis, scroll on down. Get hyped.
All of this is transcribed on Arcanum, and you can listen to the audio from the man himself at the links below.