I'm going to defend this woman because I think it's the only correct and civilized response to this situation. The fact that she wore this costume and tweeted it to her friends may have been silly on her part. However, it was wrong of her to lose her job over it. She has freedom of expression in her private sphere. Also the place she worked for didn't seem to have an issue with it at the time. Finally, the people who caught wind of this picture and got all hot and bothered over it waged a massive cyber bullying campaign against her. She got punished by lynch mob rule.
To put it into perspective, I think you'd be hard pressed to find any member on this forum who hasn't posted something stupid or offensive at one time or another. How would you feel is someone took an "offensive" post you made in P&N and used it to wage a campaign to take away your job? Probably pretty bad, victimized even?
At some point, we decided as a society that mob rule it the correct rule. Which history has shown is rarely the case. Just proves you just need a couple hundred people to be sufficiently "outraged" to take away someone's living and destroy their lives. Each one of these people who attacked this woman should be charged with stalking.