His update wasn't complicated. "It was a simple problem," he told me over the phone this morning. "One of the buttons stopped working because of a stupid error. I missed a break in a case statement." So he uploaded his bugfix at about 11 PM local United Kingdom time.
Just before midnight, he checked his e-mail before heading off to bed. The Apple approval was sitting in his in-box. A recent update, submitted last week, had taken only a day to receive approval. "With 24 hours, I was very impressed. But one hour? I couldn't believe it. Clearly Apple has changed the game."
Update: This picture speaks a thousand words. Courtesy of Tom Harris of InsiderApps. This is a different app from Jonson's