The exchange rate between one currency and another is assumed to take into account a lot of things. Certainly the strength of Countries economy and projections as to where it's going is part. Right now however we're seeing more weight based on the flow of money into the most liquid currencies of the largest economies which means the US Dollar gains temporary strength.

Personally I love this exchange rate as I invoice my customers in US Dollars but pay my people with Canadian Dollars. Saddly this won't continue and C$ will claw back some loss when current financial 'panic' dies down. Today I'll sell as many US$ as I can to take advantage while it lasts.