"This" being an upgrade waitlist for international flights. Note that it's possible to get waitlisted for a mileage upgrade when you ask for it at the gate -- or, at least, it seemed possible in SFO recently, when I was booked on a K fare. Upgrade didn't clear because affaires was full.
I don't want to beg at the airport, there should simply be an upgrade list which clears as soon as O-class becomes available.