I was talking to a telco executive a year ago, and he mentioned something interesting. “You know what’s weird about the phone?” he asked. “The fact that when you pick up the receiver to call someone, you don’t know if they’re going to be there. We’ve done all this incredible innovation in interesting new tools for using the phone — call waiting, voice mail, forwarding. But it’s kind of weird that the phone is essentially, still, a blind instrument.”

I was talking to him for a story about “presence management” — a new field in our mobile world. “Presence management” is about building tools that let you know where your posse is. The ur-application in this field is the Buddy List on America Online’s Instant Messenger. By letting you know whether someone is online or not — with those wonderful acoustic cues of a door creaking open or slamming shut — AOL’s IM beautifully defined the art of presence management.

When you launch IM, it’s like walking into a party, where you scan the room to see who’s there. It’s such an intimate feeling that, when I log on and spot someone I’m currently having a fight with, it’s very socially awkward. It’s precisely the same discomfort you feel when you walk into a party and spy someone, off in the corner, with whom you’ve had an argument. What should you do? Should I walk over and say hi? Should I ignore him? What if he looks over at me? This spatial dilemna is precisely replicated in IM: Jeez, he’s online. Normally, I’d shoot him a quick IM to say hi. Should I? Does it seem awkward if I don’t? What if he IMs me first? IMspace is, in many ways, a very tactile and physical place.

So the question is — why aren’t phones like this too? How come when I turn on my cell phone or arrive at my desk, I don’t have an option that lets me signal my availability to the outside world? When I pick up my phone to make a call, how come I don’t see a screen letting me know if the person I’m about to call is available? AOL IM — and, indeed, every messaging application — lets you neatly put up a little flag to alert others to your availability: I’m busy! I’m out at lunch! Why don’t phones have this simple, elegant application?

It’s such a no-brainer of an idea that apparently Japanese teens have figured out a simple hack to implement it. According to this very-cool story about mobile-phone culture in Japan, the kids use texting as a way to ping one another:

Before initiating a call to a keitai, they will, almost without exception, begin with a text message to determine availability; the new social norm is that you should “knock before entering.” By sending messages like “Can you talk on the phone now?” or “Are you awake?” text messagers spare each other the rude awakening and disruption of a sudden phone call.

(Cool-discussion alert: There’s a nifty thread about this in the comments for this item.)

(Thanks to Slashdot for finding this one!)