Pretty funny. Yahoo attempted to slip one by it's users, including me, by changing it's marketing preferences pages without notifying users. They claim now that notices would have gone out by email soon to let people know that they could adjust their preferences (from the default: "Please spam me!!!! ... A LOT!!!"). Being a big weblog browser, I heard about it before it hit the news, and promptly adjusted my preferences.
The truly funny part is that my 'marketing information' lists as my email address: firstname.lastname@example.org. Not my personal email account. So they'd be spamming their own mailboxes. Funnier still is that they'd cancelled my email account due to inactivity on my part (not surprising since I only ever used it as the reply-to address when I feared I'd get spammed by someone).
Make no mistake. I'm not a customer of Yahoo. These are free services, and they have to pay for them somehow. But trick spamming is not the answer. The only blessed solitary service I use from Yahoo now is the NOVA mailing list, which was originally part of eGroups, before Yahoo bought it. If Yahoo asked me to pay, in lieu of advertising, and the price was reasonable (our average volume is around twenty messages a month, with peaks of a hundred when people are feeling cranky), I'd just buy it. I think $10 or $20 a year would be fair for such low volume.