My apologies. First, I totally forgot that the Kindle DX and Kindle 2i don't have WiFi - just 3G. I then managed to track down a wireless coverage map on Amazon's website (the link to it is on the Kindle DX page at
http://www.amazon.com/Kindle-DX-Wire.../dp/B002GYWHSQ) which shows that much of Canada isn't covered (although most or all of the major cities and urban areas in Canada do appear to be covered).
So... the Personal Document Service is available, but for some in Canada, it might only be workable if you're able to use your registered email address to download the converted document to a PC or Mac, and then transfer to your Kindle via USB.