So there's a lot of conflicting information out there.
For those who have not yet applied, the according to the most recent application guide, IMM EG7000 (07-2009), police certificates must be submitted WITH the application to the local visa office AFTER you receive approval from CIO.
http://www.cic.gc.ca/english/pdf/kits/guides/EG7.pdf
"You may begin to gather your police certificates before submitting your application to the CIO. Although you will not submit the police certificate to the CIO, you must be ready to submit them to a visa office if your application is recommended for further assessment at a Canadian visa office. When you submit the application to the visa office please ensure that your certificates were not issued more than three months before you submitted your application to the CIO.
For applicants requiring multiple police certificates, please be certain these documents can be produced at the time of the submission of your application to the Canadian visa office."