" "The Canadian dollar, a commodity-backed currency, first achieved modern-era one-to-one parity with the U.S. dollar on Sept. 20. The U.S. dollar has fallen 17.5 percent against the Canadian loonie this year. Canada is a major exporter of oil, benefiting when those prices rise."

During the 60's the Canadian Dollar was worth more than US dollar. Though I suppose you could claim that the 1960's were not part of the modern-era.

" "The fundamentals (behind) that drive appear to be solidly in place and will likely fuel the Canadian dollar higher in 2008," said Michael Woolfolk, senior currency strategist at the Bank of New York. "If this continues for another year, there will be growing concerns about the currency's valuation." "

It's probably more than merely oil. One major factor is the Canadians are lowering their govt spending so that now their national debt is around the same as the US or lower [per capita].
There is also less threat of Quebec leaving Canada- that kind of thing makes some people nervous.
And they have the conservatives in power.
But there is no doubt that being a major energy exporter [they also export electricity to US] can only strengthen their dollar.