Monday Note had an interesting piece recently about the "subtle shift to Twitter". The article dealt primarily with the growing frustration of users with Facebook, and how they are migrating to Twitter for the things that Facebook is not, basically, it's simplicity. The article goes into detail about the rise of Twitter in a news perspective (e.g. Walt Mossberg at the Journal has 874 "likes" but he has well over 250,000 Twitter followers.) The other point the article makes is that the 140 characters is so mobile device friendly, it works perfectly with how we're consuming news and information on our mobile devices.