On December 1, 2010, the Japan Post will end its temporary ban on shipping packages over 1 pound (453 grams) shipped airmail to the US and its territories.
Thanks to Sophie for the information!
Addendum from a friend who went to the post office: “There’s still a processing delay which causes everything to take three days longer. The sign said the delay would be in effect from Dec. 1- 31. So, if you’re sending airmail for Christmas get it out before Dec. 10th.”