I dug up some specific information about their anatomy. It's a little bit scarce, but it's available, and because I know there's a lot of confusion and debate on the subject, I thought I'd post it here. Basically, their fangs, which are located on the top rear of their mouths, do not channel venom at all. They're just solid enlarged teeth, used to cut and tear the skin of the toads that they catch. The venom, which is produced by small glands near the back of the jaw, is secreted into their saliva, which seeps into the wounds created by their teeth.
Their venom is classified as type 1 on a scale of 1 - 3 in rear fanged snakes with these glands. 1 being fairly harmless to humans and 3 being potentially deadly. The severity of a person's reaction depends on the amount of venom that gets into the bite, and the person's sensitivity to it, but in the bulk of cases it is harmless. Most people will experience some swelling, some people don't react at all. A couple of people have been temporarily hospitalized, but no one has been killed by even a severe reaction. This does mean that if you're bitten, it is unwise to allow the snake to remain latched on for any length of time. The longer it is attached, the more exposure to the toxins.
I wrote it up and kind of simplified it here:
http://dwellsinshells.wordpress.com/...ognose-snakes/
I thought it would be handy for people who are new to hogs, but worried about the bite.