I'm not overly worried. It was *briefly* back up ~15 minutes after it first went down, and the timers for the daily event quests had been bumped up to 20 hours. That said, if this maintenance goes on for too much longer, there will still be problems.
I *suspect* the first maintenance was for the the timer thing, which was a quick fix. This downtime is presumably for the gem thing, which they be having trouble figuring out.