It’s written from an abuse-desk point of view, not a legal or "email marketing strateg-ery" point of view. I’ve had to shut down quite a few MailChimp customer accounts who grew their email lists from contests. Not that contests are bad. There are just a few pointers to keep in mind.
Speaking of Practical eCommerce, they just went through a huge website revamp, and it’s really impressive. If you’re a freelancer, web-developer, or vendor, you might want to try their new online directory.