Similar - two years ago, caught the edge of a gravel track going downhill, tried to steer out of it; woke up in the middle of the road with not-quite two piece helmet but no lasting damage (except a twingy knee).
I was bombing down a track in the twilight, didn't see a gate that was basically a single post across the road until the last minute, jammed on my brakes and bike fell sideways, I skidded along on my side (still attached to bike by SPDs) and my head hit one of the gate posts.
I was out for quite bit, woke up cold and with trousers shredded on left side. Was in a lot of pain for a couple of days and ended up with a spectacular giant hematoma on my left hip.
My first reaction on coming round after being knocked out was, of course, "I hope nobody saw that" :-)
Edit: I kept the helmet (or remains of the helmet) for years to show other people.
Hah, my first reaction was "damn, we don't have cameras!" - I wanted to see just how quick things happened and what I could/should have done differently.
Otherwise basically the same for me (I'm told) - bike slammed over onto the right, walloped me into the road, and then skidded along the ground with me still attached and out cold. Knee and right shoulder blade were skinned but that was it.
I didn't have time to react to get my shoes unclipped - SPD pedals are actually very easy to unclip from. I don't think it would have made any difference if I had unclipped - I was still going to be in trouble one way or another...
NB The accident was completely my own fault (tired, went cycling after a 250 mile drive, getting dark, out alone...)
