There has been little in the way of official information as of yet, but it seems to have originated in the vicinity of the cliff at Horse Tail Falls, the high vertical wall just east of the main cliff of El Capitan. I only had time for a cursory examination, but I think the impact point is the white rock on the cliff just above the tips of the trees.
There are white streaks on the dark gray cliffs above the white rock that may be impact scars(click on the photo below for a larger image), and lots of fresh looking boulders on the slope below. I can't tell if trees were snapped off or not. I would appreciate any reports or additional from climbers, hikers, or anyone who was in the meadow below. I will gladly post any pictures, too!