In social software there's a big and important gap between the possibility of a social behavior and the existence of that social behavior. In this case, your th

In social software there's a big and important gap between the possibility of a social behavior and the existence of that social behavior. In this case, your theory (shared by TechCrunch apparently) seems to be that Facebook, which has proved that there is an enormous market for private social communication, is going to develop a massive volume of public postings, public discussion, and become a destination site for following public discussion. Here's my theory: no way. - Defaults rule. If the facebook default is for private than that will be the bulk of conversation and that will set the expectation about how to respond (i.e. it limits forwarding of good posts to strangers). - Both sites benefit from being simple and easy to use. For Facebook to suddenly imbue every activity (posting, reading, and finding friends) with an understanding of access controls would make it a much more complex site to understand. Facebook may be copying features, but I don't think it has a chance of becoming the primary tool for public asynchronous messaging any more than it has of becoming the primary blogging platform or primary email platform. Twitter, is not copying Facebook features because those features don't support its goal for public discourse. Instead they are developing deep contacts with media. In the end, Facebook may end up with more users than Twitter, but that's an indication of the size of the markets not of one company beating the other. Both sites grew last month by the way, so it does seem like talking about the demise of either one is backward. Twitter's 6% monthly growth rate compounds to more than 100% per year (if only my investments would do that).