Guys, read here:
http://store.apple.com/ca/browse/hom...mco=OTY2ODA2OQ
Specifically:
When you purchase your iPhone from the Apple Online Store, you’ll get it commitment-free. So you can sign up for service with the carrier of your choice and change your carrier at any time.
This means that the iPhone 4 will be released in Canada with no contract or carrier lock. This also means that the Apple online store Canada will sell the iPhone 4 for full price (possibly 599/699 CDN) with factory unlock!