http://googlevoiceblog.blogspot.com/2009/08/calls-to-canada-are-free-again.html

In addition to making free long distance calls within the continental US, you can now call Canada for free through Google Voice. We offered this feature in GrandCentral previously, and in an effort to provide as many useful features as we can for free, we're happy to bring those free calls to Canada to Google Voice users as well.

So can canadian users now use google voice?

No, but calls to Canada are free for American users..

yeah Dpic, thats crazy.. I am waiting for Gvoices for Canada!!