Looks like you got charged $0.015 per KB for data in Canada, which seems about right for what Blackberry and Smartphone users are charged.
Here is a clip found in the iPhone Agreement about Int. Roaming:
-International Roaming: Substantial charges may be incurred if phone is taken out of the U.S. even if no services are intentionally used.
http://www.wireless.att.com/learn/articles-resources/iphone-terms.jsp
Looks like a data plan is offered for $25 a month that allows 20MB data transfer, with $0.005 per KB overage.
International roaming is expensive since your provider gets charged whatever the other countries provider wants to (in this case, it was probably Rogers).
Live and Learn.