I got one of those "Yosemite National Park Ticketed Entry" passes on the first day. Unfortunately the site was slammed, and may have had some initial bugs, because I got stuck in the hole with this message: “You look familiar! This facility only allows a reservation of 1 ticket per day. Please try a different date or modify your existing reservation.”. I had to create a new login each time, and finally on the third try, finally was able to book a pass for next week.

Looking at the system tonight, I see there still even 15 slots available for tomorrow. Saturday is booked, but hundreds for most days ahead.