Hi photorama,
In case your question was regarding the new optional return process that we'll be introducing in late May, the answer is: You do not have to accept international returns if you opt into the new return process. When you list an item, you will be able to indicate the countries you want to sell to, just like you can today. As stated in the previous eBay response, if you do not want to accept returns from anyone outside of the US, then do not make your items available to them. Just set your listings to be available to US buyers only.
In addition, even if you otp into the new return process when it become available later this year, and sold an item to someone outside of the US, at this time the new return process does not support international returns. So you'd have to handle the return the way you do today - outside of the new return process.
Here's a link to the Returns page in the Spring 2012 Seller Annoncement. There are FAQs at the bottom of this page which can provide you with a lot of valuable information:
http://pages.ebay.com/sellerinformation/news/returns.html
I hope that helps.
rlewczyk
Seller Communications