yes it does work in canada. you may have to register your location through your wifi routers mac address first with skyhook. skyhook data is what is used to locate you and others while using near.
just take note it can take upto 2 weeks once you register for your information to be added into their database and be operational.
I was wondering the same thing. I live in Nova Scotia, Canada and got my vita the end of March. I couldn't obtain a location from the start. I recently travelled to Spain and on crappy hotel interenet connection, I was able to connect to near and see others playing around me. Now that I'm back home, it doesn't work again.