I have no idea who it is for. I'd rather be doing stuff than telling everyone about what I'm doing.
I don't really get the self-absorbed stream-of-minutia thing.
One of the goofiest messages I saw was something along the lines of, "I'm at a bar with a hot chick, having a drink."
I'm sure that went well.
Twitter seems to be more for "Announcing" rather than communicating.
Maybe I'm just not well connected enough, but I really doubt anyone in the world cares what I'm currently doing day to day. The people that do care, I communicate with via more appropriate methods.