What's up with catnip?

I asked Cecil about Catnip before, but never saw anything posted on it. Now that straightdope.com has such a funky search system, I queried for “catnip” and found What is it with cats and catnip?, only to find that Cecil knows about as much as I’ve been able to find on the topic, which is squat. No one knows why the little critters go so wonky when they get a whiff of the stuff. I’ve lived in various areas of the mid-west, and have found it literally growing everywhere. In my present station of southern Wisconsin, it grows prolifically, and according to my cats, it’s reeeeeeal good stuff, man (they best they’ve ever had.) It’s tough to keep them away from it. Should I? Will I come home from work one day to find them catatonic? (sorry about that - had to do it).

I just don’t know, and it’s difficult to find anyone who does. Why does this nepeta cataria, the little mint plant that can, affect cats not only so strongly but so quickly as well? Once Mittens and Pooky (not their real names, I gotta respect their digninty) get a little sniff, they’re instantly transformed into slashing, meowing, freaky things that’ll do anything to get their paws on more. If part of you is in the way, say, your hand, or maybe an arm, they’ll attempt to go through that, too. Sounds spooky, don’t it? Does anyone know how this stuff actually works, what (if any) long-term effects are there, and are twelve-step recovery programs available?