Tax implications in Canada of buying and selling Bitcoins?
Taxing authorities consider currencies or goods received in trade to be taxable income. Bitcoin would fall in the same category as foreign currency or barter, and would be taxable.

In Canada, barter is sometimes exempt from taxation:

"According to the Revenue Canada document T-490 (Barter Transactions): if the person(s) bartering is an employee, and not a business owner, they may exchange non-business-related services or goods "occasionally" without being subject to taxation. However, if the goods are business-related, or the exchange is "a regular habit" it falls under the category of taxable income, regardless of his employee status." source

Here's the Revenue Canada bulletin on barter and taxation:

http://www.cra-arc.gc.ca/E/pub/tp/it490/it490-e.txt