On top of the HomePod firmware release a few months ago, which appeared to be accidental, someone in Cupertino leaked the gold masters of iOS 11 a few days ago, which appears to be intentional. The gold master is usually the final version of a new operating system for developers to use in preparing their apps before the update releases. It always gets released after Apple's keynote and includes additional bits that were previously kept secret.
Looking at the gold master reveals a lot of information that Apple would have preferred to surprise us with at the keynote. I won't spoil anything here but if you'd like to learn more, I'll just point you at MacRumors, which, as always, is pulling every morsel it can out of this leak.
The interesting, and perhaps sad, part of this is that in years past, leaks about Apple products always came from the supply chain in China. Once production ramped up to make millions of phones before launch, it was only natural that a few random parts and photos would make it to the Internet. Cupertino, however, always seemed like it was locked up and rarely did we get software leaks from the Apple headquarters. However, this year that changed. Nearly all the significant leaks came from the mother ship. This must be driving a lot of people at Apple nuts.