Erika Lo said:
Here: http://www.cic.gc.ca/english/visit/visas.asp
It seems there is a difference between "holders of the ordinary passport issued by the Ministry of Foreign Affairs" - who do not need a visa and therefore can send a copy of their passports for PPR - and people who do not hold such a passport, who do need a visa and therefore they DO need to send the passport to get the visa.
You need to send the passport if you need a visa to enter Canada. The visa they put in after PPR is a special one, good only for one entry, after which you will become a PR. If you can enter Canada without a visa (forget the stuff about ETA because everyone but Americans will need that), then you can send just the copy because you will not need the single-entry visa.
Doesn't your PPR letter tell you what to send? And congrats after your long journey to PR! You must've entered Canada a million times by now - did you need a temporary resident visa as well as your student visa? If you did - send the passport!