Do it. For European buyers such as me it's very frustrating how few sellers on US Ebay will ship abroad. I send stuff to America all the time, and I cannot imagine doing it the other way around is any more difficult. Also, I don't really know about buyers from other countries, but from a British perspective American stuff is extremely cheap, so your overseas bidders may well be willing to pay more in dollar terms than you would get from a domestic buyer. Be sure to check what payment method the potential buyer intends to use in advance - I'm no fan of Pay Pal, but they certainly are the easiest route. American bank transfers and cheques (checks) and money orders can be paid into British banks, but are expensive, so I expect the reverse is also true. I actually accept cash payments in dollars and euros, and find quite a few overseas buyers like that option despite the disadvantageous exchange rate I charge. Finally, remember the various on-line translation services such as Babelfish if you have a non-English-speaking buyer.
I suspect there are lots of overseas buyers surfing on Ebay.com, because the range of items available and the prices are so attractive compared to what's available on the various European Ebay sites - if you can show that you are willing make an effort at your end to accomodate overseas buyers you will be one of very few American sellers that do, and you will get bids as a result.
Jeremy