If Facebook sneezes does the network catch a cold?

Via the Norman Lear Center for Entertainment this interesting thought: Can you "catch" altruism or benevolence - or overindulgence or obesity - from a social network? The provocative question links to a piece at the Edge that describes a unique experiment by sociologist Nicholas A. Christakis. If it is true that the tools we create create change in us, then how will social networks and pervasive connectivity alter our behavior?