They accept them internationally provided you meet the T&C's of the BB in question, usually a two night stay at a "public rate".

However, that being said, the conversion rate ranges from OK to really bad. If you have a choice, use them in the US where the value is 1:1. If you use them internationally and have a choice of countries, check the conversion rate first. Occasionally I have gotten a good exchange rate, most often not.

Billy