For those interested in the whole Twitter scaling / business model talks, Om Malik has a pretty good idea of how to monitize Twitter, although there are also a number of good counter points in the comments, I think adding a vetting process to who follows you would take care of most of them.
I also think—until the last 7-10 days where it’s gotten worse and nearly unusable—people should take into account the total “freeness” (not even advertising) of the service when bitching about up time, my internet provider, for which I pay $80 including TV, is almost as flaky as Twitter was a month ago and I wasn’t bitching about it as much as Arrington is about Twitter. Get a grip and some perspective, especially when using it as a broadcasting service for marketing instead of a messaging service among friends. (Again, last 10 days excluded)