That's a user-agent based approach rather than an IP-based approach though. It's a difficult problem--cURL for instance allows setting the user agent header to any arbitrary value, so if I see strangeness in my logs, I ban by IP at that point. I don't know of a scraper blacklist, although some people do block a certain heavily populated country in entirety.
homeblock, there's a copyright infringement clause in the FAQ. Whether or not you believe it applies to you, you can expect complaints to start rolling in to AdSense (and any other sponsors you line up) rather quickly after you go live.
Thanks for all your input. If I go ahead and do it I won't use adsense or only on the front page. But the site I got the idea from is running it. And for some reason any pages it parses that already have adsense code come up contextual.
OTher pages only show firewall and proxy type adds that you would expect.