Why is it so hard to create a Twitter alternative that's popular and effective? Does the world tend to gravitate towards single standards for these things, like Facebook, HTTP or email?
Little guys like App.net won't stand much of a chance against the behemoths until the U.S. legalizes competition against the tech cartels.
Once that happens, sites like App.net and Twitter can compete on an even footing, and consumers will be free to choose services based on merit rather than lock-in.