When you think of product design secrecy, we're always thinking about Apple. They keep a tight lid on things, but now, it looks like it's common with all major technology companies. Samsung revealed that the Galaxy S III was developed in secret, and now Microsoft explained to TechRadar that it developed its new Surface tablets under a similar tight watch.
Microsoft's hardware unit formed a special wing to work in an "underground bunker" according to Stevie Bathiche in the division, before they moved to a more conventional building with an "airlock" door.
While we don't know if anyone else was aware of the development, which we can probably say no otherwise there would be rumors already, we can say that the end product was really well received. Can't wait for it!