Boy, that's a loaded question. I think most importantly, it has broken down the personal communication in family relationships. The kids are busy on the WII or other video games, Dad is on the computer looking at inappropriate content, people spend hours on facebook, email, blogging. they text while driving to family events, text while they are at the family events, they text at the restaraunt.
I know someone who said he and his wife went out to dinner with two other couples. Every single person was texting while they waited for the server. The guy was so disgusted he sent out a text to the others at the table and said, are we having dinner or what. I'm here where are you?
I have heard about pregnancies, decisions and actions to adopt a child, engagements, out of state moves etc. from my own children on Facebook. These messages were meant for the general public, not to me specifically. A couple of times my daughter-in-law made a delicious meal for my son, and he FB her to say thank you. She says thank you, and come to find out their in the same room using their I-pads.