I know this thread has died away, but I wanted to bring it back just to let people know that I did a search on google.com for "canada post rate increase" and came up with this webpage:
http://www.canadapost.ca/business/corporate/about/newsroom/pr/archive-e.asp?prid=924
The jist: Canada Post announced, in July, the rate increases that will come into effect in mid January next year.