From the onset, Apple's been telling us its Watch uses Wi-Fi (along with GPS) in your iPhone, but omitted that the gizmo can also take advantage of known Wi-Fi hotspots for limited functions when the paired iPhone isn't nearby or connected to the cellular network.
This nifty little feature lets the device be used standalone for the basic stuff like sending and receiving messages, drawings and taps. Just to be sure here, it still requires an iPhone to send and receive phone calls, run third-party apps and for much of its functionality, really.
The revelation was published as a side-note in Apple Watch reviews by both The Wall Street Journal and Yahoo Tech yesterday.