I've shipped from the US to Australia on several ocassions and I've never had a problem. Australia seems to have a pretty efficient customs process and postal service. Out of the other countries, I would rank them #1 and Canada, #2 in terms of good shipping experiences. Other countries I've shipped to have been OK, but items are more likely to get hung up in Customs, so I'm a little more hesitant to ship to them. Generally, the only items I'll restrict to US only are the extra-cheap items, unless somebody from another country wants an item really badly. In that case, I'll reconsider.
Heather