We should be thinking more seriously about the ethics of live-tweeting: when is it appropriate? When it is, what should and shouldn’t you do? In Blair’s case, she seemed to think that lightly obscuring the faces of the two people she surveilled was enough to be ethical. (One face, that of a small child looking over her seat two rows ahead, was not obscured at all.)
In the CYG podcast, "Internet Outrage: Part One," Aminatou Sow suggests that a good rule of thumb is to wait until a situation is over to tweet about it. For example, in this case, the woman could have waited until she was off of the plane and back home to tweet about what happened on the plane. I think that's a pretty good rule, although I think it's best to just avoid posting about strangers at all. When in doubt, don't post it.