How much of your information do you allow others to review?
http://www.computerworld.com/s/article/9171639/IRS_DOJ_use_social_media_sites_to_track_deadbeats_criminal_activity_?source=CTWNLE_nlt_security_2010-03-17 is a neat article, one that shows US Intelligence and other governmental agencies AREN'T gobbling the information on social networking sites.
It's a good read; check it out.
My friend in Switzerland asked about my Linked-In profile, now gone. It was difficult relating the whole tangled story about my recruitment--at work!--to leap into a more glamourous career. Ya, right, a Fortune 50 doing well is something to sneer at. Grrrrrr!
And then we discussed the Aurora attack, the one that used your friends and their accounts to target you into running malware. Grrrrr!
In short, I think it's time that we need to embrace the idea that Internet posting = billboard posting. Much as the husband in the movie, "Julie and Julia", we need to realize that all kinds of people are able to correlate our postings with our stated activities. People can note the inconsistencies between our stated illness and those internet postings done despite our promised illness.
As in most things, it's what you post that speaks louder than your words.