Just in case you missed it, Mango, the next version of Windows Phone will be even more internationally enabled.

Support for East Asian languages

At Mix 11, support for East Asian languages was announced. This has come about by a modified implementation of the Metro design layout. To accommodate the bigger size of East Asian fonts, the Windows Phone design team is adopting a vertical text layout to reduce the amount of text clipping that would occur more frequently (than it already does). The vertical text will not be limited to just the date and time on the lock screen but will also be featured in hubs (panoramas) and other native apps

Market place expansion

Also, the app creation market will expand from the existing 16 to 35 countries.

Additionally, Windows Phone Marketplace will support app submission in China, Israel and Luxembourg. A web Marketplace has also been announced.

Links

http://windowsteamblog.com/windows_phone/b/wpdev/archive/2011/05/24/developer-news-beta-mango-tools-available-today.aspx

http://www.liveside.net/2011/05/06/more-on-east-asian-language-support-on-windows-phone-7-5-mango