Good stuff from Tom Warren for The Verge. This, in particular, sticks out:
The exact timing of Surface development is still a mystery though, and Panay refused to comment whether the iPad was available before work started on Surface. The official timing statement is that the Windows 8 design vision was locked before the iPad and that Apple’s tablet validated a lot of the vision for Microsoft’s new operating system.
The idea totally just came to them out of thin air. I’ll quote Marc Andreessen from a couple months ago:
There’s a pattern in our industry. Apple crystallizes the product and the minute Apple crystallizes it, then everyone knows how to compete.