Speaking with my e-commerce vendor hat on, server logs (apache, mail,
application audit logs) and other information about visitors
(especially those who have conducted a purchase transaction with
us, or signed up to our newsletter) never stop having a business
purpose - it's called referential integrity.
We want to use them to track the behaviour fraudulent users
Anyone who runs mailing lists has to keep that info to be
able to prove how and when someone opted in.
Have you ever tried getting opt-in information out of someone, especially when they know they've screwed up? You practically need a subpeona to do it. In many cases (I went through this recently with ZDnet) you literally have to play the escalation game just to rattle enough cages to get people to realize you're a: serious and b: not a kook. Oddly enough, I have the hardest time with the latter.
It'll be interesting to see what this legislation looks like when/if it gets signed. Maybe it'll finally be the extra kick I need to get some of our larger databases purged.