As cessation criteria, it's recognized that if you have acquired your permanent residency through the refugee determination system, and you have since acquired another nationality, that is a recognized ground for cessation under UN conventions. That's reflected in Canadian legislation as well. This just means that if you meet the grounds for cessation as a permanent resident, then you would have your permanent residency revoked at the same time.
On May 9th, 2012. See this statement in context.