Your application is given a UCI (Unique Client Identifyer) You will have one and your sponsor will also have one.
If you have previously had a visa of any sort for Canada, this number will be the same for all.
If you havent had / or needed a visa the number will be given to you.
Once you recieve correspondence from CIC, you will get a UCI and also a File number (for the application)
It is with these numbers that you can check e-cas (an electronic way of checking on your application without having to call the call centre)
However, I have heard some people do not have any updates on their e-cas until the last step (landing)
From my experience, once my sponsor got the AOR letter, we were able to log on using the UCI and his details to see that our information is on there.