I found this fascinating quote today:
Let's not get caught up on 21st Century Skills being [about] using a computer, social network, or mobile device. Two decades ago, Twitter wasn't a twinkle in our eye -- now it's everywhere. At the end of this century, Twitter may not be a 21st Century Tool, let alone a 21st Century Skill.converstations.com, ConverStations, Sep 2009
You should read the whole article. As a computer educator and geek it is a very interesting read. We do not need to teach Word for example but teach how to do Word Processing. We do not need to teach Twitter but how to communicate.