I'm disgusted beyond belief that not only these sort of comments and threats are being made to this woman, but that their being made by adults (I make no claims of knowing who is responsible for the threats and comments, I will not convict people simply on public opinion and hearsay, but chances are all those involved are over the age of 18). These are not teenagers on livejournal or MySpace that haven't yet grasped the concept that there is a person at the other end of the computer. These are adults that not only should know better, but should be ashamed over even thinking their behavior was appropriate.
As far as I can tell these are not teenage boys with too much time on their hands, not that it would make the situation any better but the fact that these are adults with more than three brain cells to rub together make it all that more horrible. I'd bet good money that these people would never have the courage to say half that shit to her or any other woman's face, so why do they think it alright on the internet? Do people really lose the sense that it's a living breathing human with feelings on the other end?
The commenter's to Ms. Sierra telling her that she's too thin skinned are horrid as well. Thin skinned is wailing 'omg ur so mean' when someone disagrees with you or points out that your wrong due to verifiable facts. Anyone sane would be reacting like Ms. Sierra, especially someone that does not have the money to have armed body guards. While, having sadly seen (and been the target of on a smaller scale) hazing of this sort before, I do not think most of these people would have the courage to approach Ms. Sierra in person let alone actually harm her, there are always one or two crazy fuckers in any group of people like this to make her fear and safety measures more than reasonable.
The bottom line remains that behavior of this sort is never acceptable and those that know the people responsible for the threats need to step up and alert the police. Let the police deal with the matter and let them judge who is guilty.