Here's our take: Twitter is going to be overused, overload people, who will then get turned off. There is just simply too much noise and not enough valuable "signal" to be worthwhile. I run into a case of TMI - too much information -- in that I don't really need to know that you're heading to the bathroom, etc.
Yet, I think there is real potential for a service like Twitter in several areas: 1) for small, trusted groups to keep up to date with each other; 2) publishing information easily; and 3) as an aggregator of information. Here are some more details: