If you have lived together as a couple for 12 months or more, you would be considered to be a common law couple in Canada but once you are not living together any more, at some point, you do not have common law status any more. I do not know how long it takes to lose common law status.
I think after 10 years, you should already know if you want to marry her or not. Why delay until 2012? Get married now and include her in your application.
If you really want to wait until 2012 to get married, then you should either wait to apply for PR or you should seek legal advise to find out if you can at this point be considered a common law couple or not. If you can not, then you can apply as a single person and marry later. If you can, then you could include her now.