As part of today’s Websaver that Air Canada sent out they are offering 75% bonus miles for flights booked on Aircanada.com by 23:59am EST. All fare classes (from Tango up to Executive First) are valid and the bonus applies to Air Canada and Air Canada Express flights within Canada, to the U.S., Europe, Asia, Australia and Sun destinations completed by December 9, 2012.
The 75% bonus is applied to the actual mileage earned (ie you only earn 25% for Tango fares in Canada so you will get a 75% bonus on the 25% of the flight miles) Class of service and top tier bonuses are excluded.
I would assume you can combine this offer with the current 75% Aeroplan Miles bonus for flights within Canada however there is no official wording whether this offer is stackable within the T&Cs
Full details can be found on Aircanada.com.