I don't think as many Canadians are moving to the states as they used to. The tech sector in Canada is doing quite well, and many of the American companies that people used to move down south for have offices up here (EA Vancouver, for example). Even in Victoria, tech is the number one industry, and the talent pool is good enough to support serious players in industry, locally or foreign owned.
Also interesting that there are soon as many HN members outside the US as within (if this survey reflects the truth).