I haven't heard this mentioned yet: Do we really think facebook "private" messages are in any way private, or even billed by facebook to be private? I am readin

I haven't heard this mentioned yet: Do we really think facebook "private" messages are in any way private, or even billed by facebook to be private? I am reading the facebook privacy policy and they do mention that they "... may use the information we receive about you: ...to protect Facebook's or others' rights or property..." So we have rights to free speech, do we also have rights to private speech?