I am on app.net mainly to see how it evolves. My startup (
http://tomorrowish.com) relies heavily on twitter and facebook. The network effect that made those networks chock full of pop culture and marketing hasn't happened yet with app.net, and if it does, I want to see how that happens.
For instance there was social media heavy marketing conference this week called Inbound(http://inboundconference.com) that was eating up my twitter feed, but not a single tApp was posted.