Now that the private beta rollout has begun, we are going to begin releasing details about HiFi much more rapidly. To kick things off, we've recently posted a HiFi Welcome Walkthrough that give an overview of the system as a whole:
This is hosted on the brand new HiFi documentation site:
We're still adding polish to it, but it is already fairly comprehensive. We have enabled comments on every page and are monitoring them closely. The goal is to make sure that any questions about HiFi have an answer on this site!