Presence: Hidden in public view
I'd like to send my wife an SMS. In Skype I've got a group called "Family", which includes her entry. However, she hasn't filled in her mobile number in her profile, because that means exposing it to anyone she adds to her buddy list.
I can instead create a new entry for her mobile, or enter it directly, so this isn't a massive deal. I could even hand some bonus money to a telco and SMS her from my mobile. It does serve to illustrate a bigger point, though, on how different communications systems can create value by managing privacy differently.
There are several ways of technically resolving the situation. A simple one is that I have a local copy of her profile that I can extend and annotate -- a proper object inheritance mechanism. Another is that I can request her number off her.
A more interesting one is where she can enter her mobile number into her profile, but mark it as "private". So anyone can SMS her, but they don't need to have access to her number. As an intermediary, Skype then also gives her control over who can contact her in a way that the SMS system itself fails to do.
This is a little bit like how Paypal works, where you don't need to share the details of your payment instruments (credit cards, bank accounts) with vendors -- they just get the money without knowing who you are. Perhaps someone in Skype's eBay HQ office needs to take a trip down the corridor?
Martin doesn't conceal much of his identity at Telepocalypse.
