I've worked as a US citizen in Russia for a few years. In my situation, I have to pay the Russian income tax first, then basically that is credited towards the tax amount that would be owed to the IRS. Check to see if Canada has a dual tax treaty with the US, since that is the legal formality that allows you to get credit for paying income taxes in another country. A lot of Western countries do, so I'd expect Canada to be on that list, especially with sharing such a broad border with the US. You may also be able to get credit for any social taxes you pay in Canada too, depending on how the treaties are set up for social taxes. You should be able to find that information on the US Social Security website, I think I saw it there once. Also you may be able to take the Foreign Earned Income Exclusion, but that requires residency criteria to be met. Depending on what State you were living in, you may also still be on the hook for paying State Income taxes, too. There are some states that are very lenient about breaking residency, and others that are a bitch. It's not my personal situation, but I've heard California falls into that category, and a few other states.
Depending on your situation with the FEIE, state taxes, other stuff, you might not want to give your tax filing a whirl with TurboTax, although I have heard of some expats who do...
Also, there are lots of forums out there for expats living in a certain country, and naturally they have subforums on all the tax stuff, since everybody's dealing with their own situation of it and has questions & advice to share. Here's an example of one for expats in Canada:
http://www.expatforum.com/expats/expat-tax/
Good Luck