Here is the bulletin about checking up on people during landing:
http://www.cic.gc.ca/english/resources/manuals/bulletins/2010/ob251.aspI have heard about a couple of cases of people who had problems. One family that landed in Vancouver although they were PNP nominees from another province actually had their PR visa cancelled when immigration found out that they had bought a house in BC. There was another person here who had applied through Quebec but is currently living in Ontario studying and landed in Ontario and this person has been called for a hearing where I assume they will get another chance to convince immigration they are going to settle in Quebec.