I personally can see it live now in the mobile Google Image Search results; here is a screen shot:
Here is a GIF of it in action:
Google said “starting this week, a new feature makes it easy to find quick facts about what you see on Google Images. When you search for an image on mobile in the U.S., you might see information from the Knowledge Graph related to the result. That information would include people, places or things related to the image from the Knowledge Graph’s database of billions of facts, helping you explore the topic more.”
Right now this works for “people, places and things in Google Images. Google said it “will expand to more images, languages and surfaces over time.”
So if you notice a bit more traffic from Google Image Search, this might be why…
Forum discussion at Twitter.