Apple employees with a HomePod have a new firmware version available for testing -- with older versions of the device's code having revealed much about the then forthcoming iPhone X.
The firmware is publicly downloadable, but not available through the normal Developer beta release channels. The software itself is useless to anybody without a HomePod, but enterprising developers in the past have pored over data contained in it to reveal secrets about unannounced products.
A summer release of the HomePod firmware divulged the "notch" on the iPhone X, the display size of the OLED iPhone, how Siri will deal with requests beyond music playback, and technical specifications of the standalone speaker itself.
At present, it is not clear what is different in the new release, if anything at all. Also uncertain is what firmware spelunkers will find, as there are no current rumors about impending iOS devices.
Apple's $349 HomePod was revealed at the 2017 WWDC and will ship in 2018. The HomePod is powered by an Apple A8 chip featuring realtime acoustic modeling, audio beam-forming, and multi-channel echo cancelation. It features a subset of Siri, optimized for music consumption.