It's certainly great that Facebook is taking a stand for privacy. But this is clearly more of a PR move than anything else. I mean, will Facebook really sue someone for demanding an applicant's password during an interview?
Though technically Facebook should be suing the users who hand over their passwords. I should imagine that would have the opposite PR effect.
It's probably OK for your boss to tell you to log in and then tell you where to click over your shoulder, but IANAL.
It may also sue under state law for tortious interference for inducing users to breach their contract with Facebook. (It is against Facebook's TOS to share one's password.)
"Computer hacking" laws are so bad and vague that touching any computer any way that someone somewhere doesn't like is basically illegal.
If employers accessing facebook accounts become common, the cool kids will simply switch to another site while leaving a decoy FB profile.
And we all know what happens when all the cool kids leave your social network...
Along with 'N' dummy Gmail accounts if they use Android.