I think it's pretty much lumped in the same category as general sexual harassment.
Still, it's not nearly as threatening as the real thing.
Think about it...
Like the other day some guy in my city just starts sending me pics of his penis through Yahoo!
Okay...kinda creepy.
But not nearly as creepy as going outside and finding penis pics taped to my car or something.
Or having those pics handed to me by my boss!!!
Anyway, you just don't feel as vulnerable in front of your computer as you would in person.
So I can't really see any girl feeling "too terrified" to close whatever program she's in... or, if truly desperate, unplug something.
Actually, I fear the day our country becomes so lawsuit-happy that someone tries to take a "Cyber Rape" case to court.