I was across from the climber when he fell (grey helmet in the second photo).
As Greg said above, climber probably started on Werks Up but traversed over towards Bastille Crack via the ramp on P2/3. He began to set up a belay about 5-10 feet climbers left of the ordinary belay on top of P4 of the Bastille when he slipped and fell. He left a nicely placed red camalot in the crack--unclipped obviously--when he fell. I saw him fall 10-20 feet to a ledge, hit, and then tumble out of sight.
My climbing partner was working her way up to the ramp at the time of the fall, and was able to traverse over to the injured climber and remain with him until rescue arrived.
It's unclear exactly why he fell so far. He had placed a .4 camalot about 10-15 feet below where he fell. The cam held, and the rope was still clipped to the biner. However, to my understanding, he fell anywhere in the range of 50-80 feet, and probably on the higher end of that range. I'm not sure if there was too much slack in the system or the long fall was due to another factor, but it seems that we can rule out poor/no placement as the cause.
I'm glad to hear the leader is expected to recover as we hadn't heard anything since the day of the accident. Serious thanks to the Rocky Mountain Rescue team. They arrived quickly and were extremely professional.