The U.S. Supreme Court has shut down most of those lawsuits (see, e.g., Daimler v. Bauman decided by SCOTUS this month).
I'd not be surprised at all to see Canada allow suits against operators of American websites for allegedly libeling canadian citizens. It's not near as much of a stretch, since the internet extends to Canada.
No doubt that Canada can do that but, unless the American defendant has assets in Canada, it won't do the plaintiff any good. Under the SPEECH Act (passed unanimously by Congress in 2010 and signed into law by Obama), a foreign-court's libel judgment cannot be enforced in the United States unless the foreign country's libel laws are at least as protective of free speech as U.S. law.
I didn't know this!! I'm so glad to hear that! I'm going to read the case you cited above regarding hyperbole on the internet, too. I've been looking for something like that for another case we are involved in!