I never saw an official announcement. But I tested slacker.com yesterday, and it is now available to Canadians.
And it isn't that they accidentally stopped geo-blocking Canadian IP addresses. Their signup for their "better" non-free service now allows you to change country to Canada.
The problem is, of course, that it has been so many years since Slacker debuted that I "forget" why I even cared about them. Competitive technology may also have passed them by. i.e. - everyone who wants one already has an iPod.
Truth be told, given that truly portable and car Internet radios are not yet popular (i.e. - cost too much, thanks to exorbitant cellular data pricing), there really is a place for the Slacker Portable concept -- a device that downloads several hours ahead of what you are listening to so that you won't be stuck when you are out of Wi-Fi range. They now offer apps that will create a Slacker Radio in software on your Blackberry, iPhone, Android or Sony Walkman (No, not your 1982 model).