Third, there’s a big button below the crown, again on the right side. Apple showed only one function for it: Press it to summon the icons of the people you communicate with most frequently, in order to send them texts, drawings, or — this is so cool — tap signals.
For example, when you want to leave a party, tap three times on your watch’s screen. Your spouse feels the same tapping pattern on her wrist, elsewhere in the room. Or you could send a silent “I love you” tap to your spouse’s wrist when you’re thousands of miles apart.
David Pogue on the Apple Watch. <— this is a great quick read btw
IMHO this is the most interesting part of the Apple Watch story. This mini-sketch/haptic communication stuff will inspire a lot of creative spin offs and experiments.
When I was a student at NYU’s ITP program, there was 1-2 projects a year like this — sharing lightweight presence and connectivity and often involving heartbeats and physical haptic nudges (“hey, i’m thinking about you”). Each project was all awesome in their own little way and you always wished they were real projects (and real projects that worked for longer than just a demo :) The Apple Watch will bring a lot of these playful themes to the masses and that’s going to be cool to watch.