SEL has a good summary of the recent Google AMA. The short and skinny is:

1. Authorship is totally, absolutely dead. Not used by Google.
2. Panda is continuous but not real-time. It rolls in waves that take months to fully process.
3. Penguin was supposed to be out by the first quarter of this year. There's no date being placed on it anymore - it will come when it comes.
4. Gary Illyes says all SEOs should get ready for and study AMP. Curiously, he also recommended that SEOs familiarize themselves with chatbots and automated assistants, too.
5. The mobile-only index is coming. It's a big project.
6. More data is coming to Search Console.
7. 34% of Google's index is HTTPS now.

The biggest item is probably RankBrain. When it came out, RankBrain was a big news item. Google said that it would have a big impact on search rankings, and that it was one of the most important ranking factors. SEOs being...well, SEOs...immediately wondered "How can I manipulate RankBrain to give me an edge?"

Gary Illyes's simple answer is - you can't. "Gary Illyes...explained that you cannot optimize or do SEO for RankBrain. He added there are no 'scores' for RankBrain..." Though it is a ranking factor and has influence. Kind of makes sense to me. It's an "artificial intelligence." Maybe in the future there will be a way to bribe it with virtual milk and cookies :P But not today!