I live in the U.S. and a couple of items I won went through the authentication process. After my next item at the threshold didn't, I contacted eBay and was told that the authentication program didn't apply for items coming from out of the country.
This was their exact response: Hi there! Currently, only cards sold through
http://eBay.com to a US buyer would be eligible for the Authenticity Guarantee. If the card location is outside the US the card wouldn't qualify at this time. We'd be more than willing to ensure that those who can make changes in the future know that there's interest in expanding the program for international orders though, for sure. Let us know if you have any other questions. We're here to help!