Interesting article. Yes Gander and Shanwick have been using CPDLC in Atlantic oceanic airspace for well over 10 years now. Most US carriers aircraft that fly those routes have been equipped with it for years as well.
It's just recently, around the last 5 years, that it has started being used in Canadian domestic airspace. With Toronto on line soon I believe that it will then cover all Canadian domestic airspace.
Although so far I have only heard it being used by international flights on routes over the Atlantic and Pacific, mostly because these are the aircraft types that are equipped with it. I have not heard a domestic flight, such as an Air Canada CPDLC equipped (FANS) aircraft using it on say a Toronto to Vancouver flight yet. Maybe they are, I just haven't heard one yet ?
I know in the US they have been doing tests with a system called the Thales Data Communications Automation Platform (DTAP) with Fed Ex and UPS in Memphis and Louisville and soon with United in Newark, but so far this only seems to be used on the ground for clearance delivery functions.http://www.ainonline.com/aviation-news/ain-air-transport-perspective/2013-02-11/fedex-begins-data-communications-flights-memphis