Thank you sir for clearing that up. I guess I shouldn't have trusted the paypal website payments pro support when they contradicted each other.
The documentation you told me to Google up also confirms what you said, right on the top of page 15, first page of Chapter one :).
I am supposing however that if a credit card were to automatically convert it's native currency to USD at the time of transaction that things would work, assuming that the credit card being used has that feature.
In any case this is important to consider if you are a merchant who wants to do international business using website payments pro as a payment gateway.
The credit card would need to be tendered in USD. The issuing bank will gladly convert that to the card-holders currency at the wholesale conversion rate, then tack-on a "currency exchange fee" of a couple percent or more. (It's a CPU-intensive calculation :-).