[nmap]

The problem isn't just the information posted to such sites; rather, the information acquired at such sites provides a gateway to many other things. Even if one is fastidious about OPSEC/PERSEC on the specific site (facebook/myspace), the sites provide key information.

For example - let us suppose that the admiral mentioned above provides nothing but his city and state, along with his name and a picture. In at least some locales - mine, for example - one can use the name to search the public information at the property tax office and the country clerk's office. In most instances, this provides the name, physical address, and other useful information.

One can then put the name into Google and get further information. Subscription based databases (publicdata.com, Knowx.com) provide further depth for a cost that ranges from negligible to modest.

In addition, if one "friends" those at such sites, one generally gets access to their other friends. It is not unusual for people to automatically approve "friend" requests. That provides quite a lot of information to someone who one may not really know.

No doubt this is mostly old information to some here.