What would you get if you took a blog, an instant messenger, and a social network and mixed them all together in a blender? Probably something like Twitter. A mini-blogging service that lets you update your friends on what you are doing at that moment. Twitter allows blog posts of only 140 characters, which is just large enough for a sentence, or two if they are short. These messages, called tweets, are then sent out -- via web or mobile phone -- where your friends can find them.
Stephen Fry on Twitter: