According to the newest database published by the World Bank, Saudi Arabia's GDP (PPP) has edged out Canada's in 2012.
GDP (PPP) in 2012:
GDP ranking, PPP based | Data
Saudi Arabia - 1.462 trillion international dollars
Canada - 1.435 trillion international dollars
This is historical as no country in the past century with a smaller population than Canada's was able to overtake Canada's economic power.
As well, we can see that other major emerging/developing countries, such as Turkey, Iran, Nigeria, Taiwan, and Thailand are quickly catching up to Canada.
However, at market exchange rates, Canada's economy is still way ahead of Saudi Arabia's.
GDP (nominal) in 2012:
GDP (current US$) | Data | Table
Canada - US$1.780 trillion
Saudi Arabia - US$0.711 trillion