I bought a refundable ticket in A$ a couple of years ago, using a US$ credit card, and applied for a refund a couple of days later. The refund was in the original amount of A$. Both were converted to US$ at the exchange rate in effect at the time of each transaction. Since the A$ had gone up a bit, the refund in US$ was a bit less than I had paid.

(Why did I do this? Dig up the 2005 OzFest 2 thread and read about the SYD Qantas Club caper.)