I figured a ten-minute delay hours in advance was a bad sign, and the delay was likely to get worse! So I asked the check-in agent if there was an earlier departure I could take that would get me to Ithaca tonight. I really never want to be stranded overnight in Pittsburgh again.
He rebooked me Atlanta to Charlotte to Pittsburgh to Ithaca -- I'd reach Pittsburgh earlier and get my original flight back to Ithaca with a safer margin.
Just looked up my original ATL-PIT flight. It arrived on the nose. :-P
Sadly, the Original Oyster House had closed their kitchen before I got there. They'd have been happy to serve me the beer, but I couldn't have the fried clams. Went to find food, and came back after eating a pastrami sandwich to find the gate half rolled down; the bar was closing, too.
All three flights this evening were uneventful, and full. Happily, the only empty seat on the last flight, into Ithaca, was next to me.