Another vote against using it, but for a different reason.
When put on the spot like this, a lot of really good programmers would come up with the wrong answer, but not because they don't know the concepts or couldn't figure it out. What happens is that they'll see something like this and think, "Aha, trick question!", and then proceed to out-think themselves in the response. This is especially true in an interview setting where they don't have the benefit of the IDE or Google or any other of the other helps a programmer takes for granted in their day to day programming.
