I've seen the original picture. She's definitely smiling. That's just Haruhi's personality. She just does whatever without really caring about the consequences.
For example, she forces the head of the computer club into compromising positions with a very unwilling Mikuru, then takes pictures and uses them as blackmail. If he didn't comply with her demands, she'd spread the pictures around and say that he raped poor Mikuru.
Like I said...fucking crazy.