It would be nice to have such a thing in Canada - do you know of any such organizations here?

NEADS (National Educational Association of Disabled Students) is a Canadian organization that helps students with disabilities in PSE and in the post-PSE world (careers, job hunting). They have a write up about students with intellectual disabilities but no mention of organizations specifically for such students in Canada.

http://www.neads.ca/en/norc/eag/inclusive.php

Other than the individual educational institutions NEADS would probably be one of the organizations that students or their parents could contact if there is interest in pursuing postsecondary education. In BC there is InclusionBC which has a mandate to support people with disabilities. They hold public forums for students with disabilities transitioning to postsecondary education.

http://www.inclusionbc.org/

ibelong.ca has a collection of resources that students with intellectual disabilities and their familities can use if a young adult is thinking about going to college.

http://www.ibelong.ca/uploads/FM_8B_Post-Secondary_Opportunities.pdf

ASD personnel at AU may have more resources on this topic.