You’re on Facebook on your computer at home, and you start chatting to a friend using its Chat facility. Then, say, you leave home but you’re using your smartphone’s Facebook app: there you can continue the chat. And if your friend leaves their computer and heads out with just a dumbphone that can only do texts, they’ll still be able to contact you. Or if your friend gets a smartphone, and starts checking their email, in time (not yet) the conversation will continue in email. A huge, horrendously long, never-ending email of your conversation.
Sounds simple to do; in fact, it is hideously complicated. Facebook has had 15 programmers working for more than a year on this, and it’s still not cooked. If Zuckerberg has solved this problem, we’ll all cheer – though if it means we all have to live inside Facebook.com, maybe not.
Read More: http://www.guardian.co.uk/technology/2010/nov/16/facebook-emailing-looks-tricky