There are few dedicated groups across Canada that are dedicated to readers' advisory. As I have stated, I am chair of Ontario's readers' advisory committee and we work on developing a yearly event and various initiatives which promote readers' advisory.
I am familiar with another organization in British Columbia which developed after learning about the Ontario committee. They are involved in many of the same activities but cover the west coast.
The Southern Ontario Library Service also offers some content for library training in readers' advisory.