The Obay ads are excellent - whether you agree or disagree with the message, it's great to see the protesters realising that mass-plastered A4s just don't compete with proper advertising. Hoping it will continue, leading to a high-graphic-design combat which can only be entertaining, and maybe even educational.
Also, they're not just in Toronto. I'm in Thunder Bay (on the shore of lake Superior, close to Minnesota) and we've got them on bus shelters, too. They've just started to show up recently.