USPS and eBay have teamed up to offer a co-branded Priority Mail shipping service. Users of eBay's online auctions will be able to ship special boxes with a flat rate of $7,70, regardless of weight or destination.
The source doesn't mention this but I guess it's quite logical that this service will only become available to users in the United States.
The boxes will come in different shapes and sizes and they will carry USPS and eBay logos. The service will become available on Thursday.