Canadian passport renewal with TN

I am getting ready to renewal passports for me any my wife. They both expire in March of 2012.

My questions are about the TN form or I94-A and if we should remove these before sending off our passports to Canada for renewal. What is normal practise for canadians working in the US. I checked the Canadian passport site and I don't see any other utopians or to mail the application and surrender the passport to Canada as part of the application.

Thanks,
P

Although unassuming, Form I-94 is a very important document that you must retain as proof of your TN status and valid US work authorization.