IBM's buzzer-buzzing robot ...
I thoroughly enjoyed the event, but I question the fairness of placing an electronic system against humans when the critical step is timing a buzzer. I'm fairly certain a highschooler could design a robot capable of beating the world best trivia-experts at mashing a button first.
Ken/Brad could have easily answered most of those questions instead of Watson, but for some reason are unable to match his 1ms buzzer response times.
Not detracting from the parallel compute power - welcome our new, redundantly animated overlord, and such - but I was very distracted by this part. And I'm also curious if Watson knows the exact answer when it buzzes, or if it buzzes and then finishes refining the answer.