We've also found lots of discrepancies in Canadian data. See
http://www.infinitegravity.ca/MapPoint.asp for a short article on it.
We've been spending a _huge_ amount of CPU time tracking down these problems for the whole of Canada. As we go along, we're creating cross-reference data to map from Canada-Post standard formats to what MapPoint wants to see to match correctly. At the same time, we're recording the coordinates for faster lookup in the next time we need to map an address.