Excuse my ignorance, since I didn't make it to last SWINOG... the description on their web site implies the system is using BGP to distribute the black list. Assuming this just distributes IP addresses of web servers hosting questionable content, by blocking those, will that not block content of ALL hostings hosted on that IP address? What about hosters who also host other services on that IP address, like perhaps DNS and mail services? I recall a time where an email RBL was implemented using BGP blackholing, and we can into exactly those problems...
Cheers, Markus