Not only did Air Canada announce that they'll be dropping their $25 second bag fee (see story below) but they've also decided to incorporate fuel surcharges in all advertised base fares, and starting October 14, will simplify excess baggage fees. Passengers will pay a single $75 fee for overweight and/or oversized bags for travel within North America ($100 for other flights).
So in other words, if you have a bag in excess of the number allowed, you won't be socked for extra charges if the bag is overweight or oversized. Most airlines' baggage fees are cumulative: you pay the extra bag fee plus any overweight charges plus any oversized charges, which can really add up. We doubt US airlines will follow suit, but you never know.