It's unclear where Apple is in terms of actual development. Bilton doesn't have a timetable for release, or even a set of features.

He simply reports:

In its headquarters in Cupertino, Calif., Apple is experimenting with wristwatch-like devices made of curved glass, according to people familiar with the company’s explorations, who spoke on the condition that they not be named because they are not allowed to publicly discuss unreleased products. Such a watch would operate Apple’s iOS platform, two people said, and stand apart from competitors based on the company’s understanding of how such glass can curve around the human body.