I think you're all missing the original questions that Dazed posed, which were:
Originally Posted By: dazed1
So...how do you feel or what will you accept? Is it... -I don't care. My W can have as many male friends as she wants on FB. -No male friends for my W. -Somewhere in the middle?
To me, it goes to "reasonable cause" and to what the past marital history is. In a healthy, mutually-respectful marriage with no prior infidelity, and with no current behaviors ("reasonable cause") to suggest anything untoward is going on, I see nothing wrong with a married person having friends of the opposite sex on Facebook. If one spouse expresses that they are uncomfortable with, say, an old flame being friended, they should speak up and their spouse should respect that and offer to either block that person or offer full transparency to their FB account, in my opinion.
If there is prior infidelity, or current symptoms of it, then all bets are off.
Guys, Facebook is just a vehicle. If it's not FB, it'll be something else -- you can't burn all the books. You gotta treat the symptoms, and -- as Dr. Harley put it in the sub-title to his classic book -- "Affair-Proof the marriage."