The problem with international shipping is import tax. Not that we can't buy with bitcoins.
Import tax will be there even if you pay using credit card.
But you will save some money on foreign transaction fee using bitcoin.
I also expect overstock to give some discount for those using bitcoins, after some time.
After all, they make some savings on the credit card transaction charges.
This is true in theory but in reality the shops usually increase by 3-5% the price if the costumer pays with btc.