The idea of providing presence data is an interesting one; basically providing a service so that my friends know what is going on with me at any given time. Figuring out who is doing what in an easy way makes it simpler to make plans more spontaneously. Right now, the best method that exists amongst my friends is IM away messages. Works ok when people are online, but most people don’t leave themselves logged in all the time, so the system falls down.
Enter twitter. It provides persistent storage of presence data. It can be delivered via the web, via IM, or even via SMS. It seems like a great solution, but granted it only works if people you know also use it. Classic chicken and egg problem. In an effort to start things up, I have signed up and I will try to start using it.