Yes, prices will drop on Apple's products, but Apple traditionally doesn't update the price on products until there is a update to the product (ie. a change in the product, or a price drop (not an exchange rate change)). You can actually see the exchange reflected on Apple's website if you compare the US and Canadian prices of the different products. The rate used for the G5s is about 0.70, the exchange rate for the Powerbooks/iBooks is about 0.73 since the Powerbooks/iBooks were updated after the G5s. I agree that Apple should probably change their prices more often, but I doubt you will ever see it change more than monthly, because most of their products are not bought and delivered in a day. It can be good or bad for both the purchaser and buyer by the way.
By the way, you'll never see any business use the exact exchange rate, so don't go comparing what's currently on yahoo or where-ever to Apple's site. With the loonie changing by half a cent to a cent in a day, the exchange rate businesses use is going to be off by a couple of cents.