The iPhone is a GSM phone, and all Canadian providers - except one - use the CDMA standard. The lone GSM provider is Rogers Wireless, which makes them the only Canadian company that can possibly support the iPhone. This past Tuesday, Rogers made a point of telling CBC News Online that they had not announced their intentions to carry the iPhone.
Note that Rogers didn't say they won't carry the iPhone at all, they just aren't prepared to say that they will. Perhaps the don't want to expose their plan too early, or maybe last-minute negotiations are ongoing.
In any case, we've got our fingers crossed for all of our Apple-loving neighbors to the north.