Influential Marketing Blog put up a post this past week with a partial theory about how information is being spread through MicroSharing.

What the argument boils down to is that there is a lot of content out there, and people need a way to deal with that content and find relevant information. So niche groups share content they're interested in among themselves (MicroSharing), with the effect that they promote some content while ignoring others. This has obvious implications for marketers who want to spread information.

It's a very interesting article (as they tend to be from Influential Marketing Blog) and worth reading. I wish it had had a few more details to flesh out the theory, though.