The AC wasn't really a "book" per-se, but a collected volume of snippets, wasn't it? I'd hardly call that a "banned" book though. I mean, it contained illegal activities which would have been verboten in most places.
When I was in high school, there were kids who would frequent online forums (and a myriad of ad-heavy free hosts including GEOCITIES!!!!) that would put up The AC, using the library computers.
They used Websense to filter content, which was about as effective as a sieve since they hadn't contemplated open proxies. 10 - 20 New ones which would pop up from time to time and the IPs would get traded on those forums.
From the copies that got passed around on floppies (aaah, floppies. Remember those?) I'd say The AC was a collection of (mostly bad) texts assembled from various authors who posted these on Usenet and the like previously. I remember there were multiple versions; nothing really "official" since many were edited and compiled by independent authors and all are guaranteed to get you in hospital or jail.
I think a couple of idiots in our school accomplished both.
No, it was a book, published in hard copy. And it's probably older than you are.
The best story I've read on the Internet about the Anarchist cookbook was a guy who claimed that he accidentally blew up his middle school with home made dynamite in Ireland, and only got away with it because the government blamed it on the IRA. (I can't seem to find it right now though.)
The fastest way to falsify that story is if the recipe for dynamite in the Anarchist cookbook is wrong. (Which it may very well be, as the book is full of wrong information IIRC.)
I googled for it and found a "anarchist cookbook v2000". It contains recipes for dynamite and nitroglycerin that are correct, but stupendously dangerous to do.
When is the last time any of those books were banned in the USA? (I chose a country where I know Mein Kampf is available to purchase and legal to possess.)