The idea is that you can keep your friends informed of where you are and what you're doing by text-messaging them from your mobile phone. If you think about it it's a pretty cool idea: You can subscribe to text messages from your friends and they can "blog" their wheareabouts and doings. So, for example, if you're going to be in a certain city, or a certain coffee shop, or a certain club -- you can text message all your friends in one go, for example: "I'm going to the Starbucks at Market and Polk. Meet me if you want to play Scrabble."
People will get your text message immediately no matter where they are -- it's more immediate than a blog or email, and if they happen to be nearby, you haven't missed an opportunity to hook up.
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