Thanks for digging out those links. I think Imran came up with it in 2006 or 2007, he was certainly experimenting with interview questions around that time, so

Thanks for digging out those links. I think Imran came up with it in 2006 or 2007, he was certainly experimenting with interview questions around that time, so the blog post was not long after. I had no idea at the time he had a blog and didn't see the post myself until a few years after that. In fact, I think I saw Jeff Atwood's first!