It is no longer possible to get a 10-day trip permit in Ontario as of 28 July 2008.
They have now switched to a 10-day temporary validation sticker which goes onto your existing plates.
In other words, when buying a vehicle, you now need to register the vehicle into your name, pay the Retail Sales Tax, and attach either new or existing plates to your vehicle, to get a temporary validation sticker. If buying a used vehicle, you will still need your safety and emissions test to get your regular validation sticker.
Another change, you are only allowed two 10-day temporary validations per vehicle in a 365 day period.