There's this post in the forums by Qaridarium, the German Phoronix reader known from time-to-time to rattle a bit. On several occasions in the past though, he has been right. He claims that AMD will open-source "important closed source stuff."
The date he gives is that this drop will take place on Tuesday, 31 May. As of right now, I haven't heard from AMD or any of their partners yet saying any drop is scheduled to take place, let alone Tuesday, the day after a holiday. There is some stuff coming down the pipeline, but if something of importance hits on Tuesday it will be surprising.
On my Twitter feed, I have hinted at another sort of drop coming, but it's not from AMD. Regardless, the discussion and speculations can continue in the forums over this holiday weekend.