Incidentally, data from the WHO on global causes of death: http://www.who.int/mediacentre/factsheets/fs310/en/index.html
HIV is the 6th-largest cause of death globally, and the largest cause as a single disease (the only infectious diseases above it are groups: "lower respiratory infections" and "diarrheal diseases". It's the 3rd-largest cause of death in lower-income countries after the two I just mentioned, while malaria is 5th and TB is 7th.
So yes, this is big. But the CBC article also said that three previous vaccines (using live virus, rather than killed virus as this one does) have gone to clincial trials and nothing has come of them, so while this is a large step forward, there's no certainty that it will be successful.
Still, impressive. Go Canada! Proud of my country's researchers.