The US Foreign Account Tax Compliance Act (FATCA) is being implemented in Canada under an Intergovernmental Agreement (IGA) between Canada and the US. The particulars are in the Budget Implementation Act currently being debated in Parliament. The upshot is that Canadian financial institutions will be obligated to send personal information to the Canadian Revenue Agency that will be shared with the IRS in the USA. The government has released some basic information here
There are substantive arguments that the IGA violates Canadian constitutional and privacy laws, and American law. However, the US has been insistent in negotiations and the Canadian government has acquiesced.
Those with American citizenship or residency may have their banking information relayed to the IRS. Canadian Banks, with some exceptions, will begin collecting and reporting information as of July 1, 2014. "US persons" affected should be assessing their positions. There is the prospect that US tax collectors will be harassing many people in Canada who have US links or citizenship. Call if you would like more information.