There are new species being found in Canada; at exactly what rate, I don't know. It varies a lot by taxonomic group. I don't think we're going to find a whole lot of new mammals, but we find new lichens, new plants, and new insects especially. So it varies by group, it varies by region, and it varies according to the density of taxonomic expertise in particular groups of organisms as well.
On May 4th, 2010. See this statement in context.