The row2k laptop and backpack that we reported missing on Friday was found; it is unclear exactly what happened, but in the end it was the very last item (along with a box of oranges) left on Sunday afternoon in the large athlete/boat field, about 700 meters from the finish line media tent where row2k had stored it on Friday morning.
At that time the folks who saw it thought it might belong to a staff member, so they texted their staff; one of the coaches had read the row2k news item, which set in motion the return of the laptop.
The whole episode could have been far less agonizing, but thank you for everyone who expressed concern and tried to help, it is greatly appreciated.