The world needs more social networks like it needs more politicians. Then again, we've got some time for Potluck, if only because the service is financially backed by Ev Williams and Biz Stone -- two guys who have form when it comes to spotting a good idea. Potluck's iOS app, which has just benefited from a major overhaul, throws curated news stories at you one by one. Then it asks you to tap "yay" or "nay" depending on whether you find the topic enticing -- a bit
