Mark Gurman, 9to5Mac:
Yesterday, we reported that the latest iOS 8.2 beta reveals that an Apple Watch application for the iPhone is in the works. Now, we have some more details. Within Apple, the application is currently called the Apple Watch “Companion” app for iPhone. This application manages settings for Apple Watch applications, as well as settings for iPhone/Watch interactivity. The Companion app’s settings reveal some novel new functions that are coming to the Apple Watch.
Details in Mark's linked post.