This kind of big brother intrusion was inevitable. We all knew it was coming since the internet was born. There aren't any safe sectors or areas of your life that the government cannot look into if they want.
I don't worry about it too much, but the time will come when abuses of access to these systems (social media) will be commonplace. Corporations are already happy to take the information you freely give away , now the government wants a piece of the pie. Since "friending" the FBI doesn't seem a likely opt-in option, they have to get access by pressure/force.
EDIT: I'm not anti-government or anything, just stating what I see. I don't care either way, I've got nothing of value to the government or anyone else for that matter.