The new vectorial topographic maps from Natural Resssources department of Canada (NRCAN), introduced in may 2009, have a superior quality as compared to the old Raster maps (see TOPO Canvec map). However, note that the new NRCAN Toporama server has a slow response time for zoom levels of 8 and under and do not show map on zoom levels 9 and 10. The map Topo-Canvec+Raster shows the old Raster map for the zoom levels 10 and under.
See discussion on this subject : Google Map API Discussion Group.
See Map application of Club de montagne le Canadien with Geolocalization.