But this is an attempt at justification, not technical advice. Perhaps a quick breakdown of the tech would be useful.
Here's where it gets interesting. The cookie is set on your domain name (apparently named 'webwise', the name they given the system in an apparent attempt to make it seem like a security feature).
If (as a user) you block the cookie, they temporarily stop the phorm redirect (otherwise it would go on forever).
The reliance on cookies set on third party domains is their main Achilles heel. Users can block them, and site owners can detect them. I've heard that blocking the cookies as a user may result in performance problems with your internet connection. As a site owner, you can choose what to show to visitors carrying a phorm/webwise cookie. Of course, you shouldn't need to bother, but that's a different discussion.
Further, from what I've read the system seems like it could be vulnerable to hacking, due to the implementation. I imagine it will also be an attractive target. I'm a bit dubious about some of the ways they seem to be handling redirects, and detecting problems.
Added: just saw your post, driller41, but see above.
[edited by: Receptional_Andy at 8:19 pm (utc) on June 6, 2008]