I've heard many complaints from people concerned about having to mail away their documents when they wanted to get a new or renewed Canadian Passport. If you go to official Passport Canada offices, they'll let you get your documents right back, but not everyone lives near an office, or is willing to wait in line.

So, I sent Passport Canada an email, and asked them if you could keep your documents (like your birth certificate, old passport, citizenship card, etc), if you went to a Receiving Agent (ie: in some towns without an office, Canada Post and/or Service Canada will take your documents). You'll still have to wait just as long as if you mailed away your application (in-person applications get priority), but here's Passport Canada's reply:

Please note the original proof of citizenship and documents will be returned to you immediately if you submit your passport application in person at a Passport Canada office. When applying in person, you must also submit an original of your document to support your identity.

If the passport application is submitted by mail/courier, the original proof of citizenship and original or certified copies of your documents will be returned to you with the new passport.

If the passport application is submitted at a Receiving Agent (Canada Post or Service Canada Centre), the original proof of citizenship will be returned to you with the new passport. However, upon request, a representative may photocopy your original document(s) to support identity, include it with your passport application and return your original documents to you immediately.

So, there you have it, in just 7 days, Passport Canada replied to my online enquiry with this nice tid-bit of information for those that are a bit afraid to mail away their only pieces of citizenship documentation. Also, note that many (all?) Canada Post locations with Receiving Agents have an extra charge for dropping off your passport application there.