Based on what I've heard, these aren't hacks on Postgres - more a pluggable storage engine. Haven't cross checked this, but I think both MySQL and Postgres have a swappable low level storage API. AWS has made engines that use their specific infrastructure to make all these changes - there are technically no changes in either the MySQL or Postgres engines themselves - only the storage layer.

That's why no announcements cover change fundamental change to either database - all the features we're seeing a the kinds you'd do on a personal scale with SSD RAIDs and ZFS (or other copy on write FSes), except on a datacenter scale.