I don’t think that the concerns many have about Facebook are unfounded.
Here is a quotation from a 14 July 2010 CNN.com article about Facebook (article titled Facebook a ‘tool’ for cheating spouses, some say):
A recent survey by the American Academy of Matrimonial Lawyers found that 81 percent of divorce attorneys have seen an increase in the number of cases using social networking evidence during the past five years. More than 66 percent of those attorneys said the No. 1 site most often used as evidence is Facebook with its 400 million registered users.
Of course the counter-argument to this is, “those who will stray will stray, with or without Facebook.” However, Facebook makes it much easier.