Huh, I had no idea. An Easter egg, almost, as I've never seen this mentioned by Google.
It works ok, send pretty beta right now. I pointed my camera at a business card and pressed the home button. Google Assistant appeared and I asked it to tell me about what was on my screen. It noticed one piece of the address, and brought up a listing for that general area, but there was no way to further inquire into any of the rest of the card.
Sorry, I should have been more clear. It's moved into the "now on tap" feature, which now links to Google Assistant. You're right though, if you ask what's in your screen it has the same effect.
It works ok, send pretty beta right now. I pointed my camera at a business card and pressed the home button. Google Assistant appeared and I asked it to tell me about what was on my screen. It noticed one piece of the address, and brought up a listing for that general area, but there was no way to further inquire into any of the rest of the card.