You may recall what happened when Amazon tried to enter the Canadian marketplace. It functions as amazon.ca, and it's largely run through the post office. Owing to restrictions on the requirement for booksellers to be Canadian owned, it couldn't function in this country the way it functions in other jurisdictions. We have restrictions on ownership, so unless Jeff Bezos happened to be a Canadian, there would be a problem. But he's not.
With something like Skype, there are ongoing issues on the telecom side with respect to VoIP. Even accessing phone numbers has been challenging. It's one of the reasons you don't see the same number of Internet telephony services in Canada that you see in some other jurisdictions.
As to the listings data, that's actually an issue that the commissioner for competition has been quite active on. MLS has been aggressive in retaining these data, so that it's difficult for other services to make use of listings data. In the United States, there is a true Web 2.0 Ecosystem for real estate data, where they build Google-like maps, street views, and a range of other data, so that you can layer it all into a much richer experience than Canadians are able to obtain.