Closed in December 2018. Looks like they had a run on the permits again, and if I read the "gusher report" correctly, the permits are all gone. (I call people "gushers" who tend to rave on about their "bucket list." What a loathsome phrase that has become in recent years.) (Read on to find out the "gushers" were mistaken, but not by much.)
A very few years ago you could walk down solo with no reservation, and they'd take your cash and let you in, no questions asked. More recently they didn't want you to do that, but instead you could wait around in the parking lot with some cash, and glom onto an existing trip, because most of those trips had empty spaces due to cancellations. But VERY IMPORTANT POINT, this is no longer going to be allowed!!! They are taking names this year, for everyone on the trip. And it costs $100 to make name alterations to the permit! This is a huge difference, and will cause many cancellations to occur, I think. You can specify an alternate trip leader, but you can't make a bunch of name changes without paying $100.
What this brings up is wondering whether cancellations will be posted on their website as soon as they occur--easy to grab for people who are watching it. Maybe there will be a lot more cancellations.
At this writing there are a few dates left in February for what I specified, which was 3 nights for one person. There don't seem to be ANY dates left other than in Feb, in fact. (I didn't book the trip, I just wanted to see what was available.)
I've been on a couple of two-nighters, and it was not enough time by a long shot, especially if you want to hike to the Colorado River one of the days, and spend another layover day just playing around below Mooney Falls. So, in my first search I only specified three nights. I could go there THIS MONTH if I wanted to book it immediately. If I booked only one night I'd have more choices, but still only in Feb.