If you do have a facebook account with your real name and a well known email address keep it for your family and all those nice happy "happy birthday mum" type status updates.
If you do want to discuss falling out a pub on the lash with your mates dont have your real name and have a email address without your name on it (like
peakdoomer@yahoo.com than
billsmith@yagoo.com).
That said automated photographic identification may make that less anonomous but hey ho, thems the modern life.
In terms of the state, well they can watch your movement by your mobile, if they have the right warrent they can keep an eye on which base stations pick you up. They can check where you shop using plastic and with the increase in RFIDs you are becoming even more watched.
Ill not be suprised if encrypted peer to peer darknets dont become more mainstream in the coming years though.
And one piece of advice always be logged out of Google when searching. They retain a certain amount of info on you to add some personal parameters to the Google searches, this means the information is being tailored and can be lead to a narrowing of your results. Ill take it as a given everyone knows the results are shaped anyway (like how wikipedia is almost always the top result).