Of course Whispernet works fine in Canada. But your @free.kindle.com address will not. Here is the response I get when I try:
Greetings from Amazon.com,
Kindle Personal Document Service is not available in Canada. We look forward to making this service available in Canada in the future but aren’t announcing a timeline today.
Did you recently move to a new country? You can easily update your country for your Amazon account at
http://www.amazon.com/manageyourkindle.
Please note that if you change your country, you will need to have the email to be resent to get your document(s).
Alternatively, you can also use our free Personal Document Service ("name"@free.kindle.com) for any document you want to transfer over USB, and you will not be charged.
You can learn more about transferring personal documents to your Kindle in our help pages:
http://www.amazon.com/kindlepersonaldocuments/
If you would like immediate assistance, please contact customer support at +1-206-266-0927 (International Customers).
Sincerely,
Amazon Kindle Support