Replying to my own comment:
As many have pointed out, this was not actually the postmortem, just an "update". I still find it pretty weak. There has been plenty of time to assemble basic details, such as a rough timeline. Yes they are busy with the actual response and cleanup, but this is a big professional team. The update feels less like "we're on it, here's what we have so far, more to come", and more like a bland PR minimization exercise.
I'll note that they've found time to determine that "For most Google users there was little or no visible change to their services", "YouTube measured a 10% drop in global views during the incident", and "approximately 1% of active Gmail users had problems", and yet they don't mention the time at which the incident was fully resolved or even when it started! Did the impact last for a few minutes, an hour, or multiple hours? Reading this, I have no idea. But I do learn that "the Google teams were keenly aware that every minute which passed represented another minute of user impact", they "brought on additional help to parallelize restoration efforts", "networking systems correctly triaged the traffic overload", and "low-bandwidth services like Google Search recorded only a short-lived increase in latency". In other words, this update on what seems to have been a very major incident consists mostly of vague, positive statements. It does say "we take it very seriously", but it doesn't make me believe it.
(I would add that I worked at Google from 2006 to 2010, and based on that experience I'm sure they are taking this very seriously and that there will be an excellent internal postmortem. But man, reading this sure makes it hard to remember that.)