So I thought I was getting great book summaries (from GPT 3.5, I guess) for various business books I had seen recommended, but then out of curiosity one day I asked it questions about a fiction book that I've re-read multiple times (Daemon by Daniel Suarez)... and well now I can say that I've seen AI Hallucinations firsthand:

https://chat.openai.com/share/d1cdd811-edc9-4d55-9cc1-a79215...

Not a very scientific or conclusive test to be sure, but I think I'll stick with using ChatGPT as my programming-rubber-ducky-on-steroids for now :)