What is interesting too, is that when going to list something for sale or auction, the default, international shipping method (at least here in the US on ebay.com) IS ebay's GPS service. So unless one isnt careful, and doesnt select another mailing option to mail overseas, GPS will automatically be used.
(Of course, a seller can go back and change it later to USPS, FedX etc, if wanted), but it's the idea that it's automatically chosen when going to list an item, that I dont care for.