As of Sep 12, Rexall in Western Canada began offering Aeroplan miles for all purchases made including prescriptions. The regular earning is 1 Aeroplan Miles per $1 spent. Stores in Ontario are not included and will continue to offer AIR MILES Rewards Miles.
The Aeroplan website does not have any more details on the partnership as their link to Rexall is broken. Apparently the official launch of the partnership will be in October with full announcements and possible promotions.