From the article:
"Google Now has a huge knowledge graph—you can ask questions like ‘Where was Abraham Lincoln born?’ And it can name the city. You can also say, ‘What is the population?’ of a city and it’ll bring up a chart and answer. But you cannot say, ‘What is the population of the city where Abraham Lincoln was born?’”
Out of interest I tried this question on WolframAlpha and it happily returned the answer[0].
You can also ask this query directly into Google's knowledge graph[1] - but the point still stands that Google doesn't have a way to formulate that query directly from a natural language sentence.
But, the answers are useless to me if they're returned as images. (And yeah, I'm aware of OCR). I'm not saying the results are returned as images right now, maybe they are, maybe they aren't, but Wolfram has pulled this stuff in the past so my trust in the service is zero.
Actually the result "3232 people (2012 estimate)" is indeed a GIF – check out the source. It looks like they use a canvas element to simulate the underline-on-hover.
Out of interest I tried this question on WolframAlpha and it happily returned the answer[0].
[0] http://www.wolframalpha.com/input/?i=What%20is%20the%20popul...