The screw actually went into the bed of the rim where the tube normally would be and made a rough burr. I had to "file" it down with a rock or risk it creating another puncture on my spare. Crazy. Still managed to get in 25 before work and saw a Bald Eagle along the way so all was not lost.
Dang! Haven't seen anything like that before, but given the crazy roads we have here in chicago, I am kinda surprised that it isn't a more common occurrence!!
It happened in a turn and made a terrible clanking noise each time it came around. Scared the heck out of me. I am afraid to look at the stays of my carbon frame tonight as that screw was sort of off to the side. I must have been standig on end to go in like that.