It looks like Apple is letting American fans of Japanese music download tunes without buying an overseas gift card. I was searching for some music on the iTMS today, and a song by a Japanese group happened to come up. It was listed under the genre "J-Pop." Clicking on this genre gave a listing of quite a few popular Japanese artists who I'm sure weren't available before. It includes Boa, M-Flo, Ai Otsuka, Beni Asashiro, Janne Da Arc and Ayumi Hamasaki.
It's not the complete contents of the Japanese store, obviously. And not all of the things listed are available yet, but some of them are.
I did a search and didn't see this posted yet, so I thought maybe it would be of interest to some people.