Marc,
We have a Capital One No Hassle Miles Platinum Visa. I do not know what index they use. On Feb 9, 2009, they gave 1.217782188 CAD for 1 US$ for a hotel bill in Montreal. The only online historical exchange quote I could find for that day was at Yahoo and it gave the rate as 1.2188 CAD per 1 US$.

Debbie