IBM's artificial intelligence software took on a major challenge starting today, as it appeared alongside two of the best players ever on the 'Jeopardy!' (Weeknights, 7PM ET on ABC) stage. It was a test of the program's abilities to respond to natural language questions, and one of the final chapters in its journey toward completion.

It took several years to get Watson to a point where it could answer questions quickly enough to even compete on the show, but audiences were delighted to see the computer hanging in there quite well against the big boys.

There were some obvious glitches, as when it answered "What is leg?" It apparently couldn't extrapolate the more complex question, "What is 'he's missing a leg'?"