Clive Thompson discusses this idea and describes it basically as being aware of what was going on in a person's life just based on their social media posts. You gain an awareness of their train of thought and the lives they lead. You become aware of their favorite things and can almost intuit what is going on their life. It reminds me of a scene in Tina Fey's Mean Girls where Karen, the on sight air-head says "It's almost like I have ESPN or something." Yes. We all have ESPN. But now, with ambient contact we can all have ESP.
I have found that ambient contact has been the greatest thing when it comes to "keeping up" with friends from high school and staying current with their mental states. Recently, one of my friends at UPenn posted a status to Facebook talking about how she was in a dark place and was feeling very depressed. She had been posting for the past few weeks about sadness, depression, and even literary quotes that line up with these emotions. When she posted the status about leaving UPenn for a semester, I was not surprised and I felt like I knew why. I immediately messaged her on Facebook giving her my support and it felt as if we had just been having a conversation about her mental state, although we had not talked for months. Ambient awareness, while some people may think it cheapens connections, deepens connections in my opinion. For whatever reason, it seems that our generation has become more comfortable sharing their emotions and life events with an app on their phone than directly to another individual.
Twitter has no face and thus it has no judgement. There is no fear of sharing things with your computer and it allows us to peek into the minds and lives of others.