Over iStartedSomething, Long Zheng goes into some detail about the East Asian language pack coming to Windows Phone 7 in the fall via Mango. Specifically, what it means in terms of the Metro design when showing such languages as Chinese, Japanese and Korean, amongst others. As you can see in the image above, taken during MIX11, East Asian languages will for the first time be using the vertical plan as opposed to just horizontally displayed words and characters. The reasoning for this should be obvious as systems such as katakana and kanji require a little more...space.
Evidently, this change is not just for the lock-screen, but for the native hubs and panoramas throughout the OS, adding a unique expansion of the Metro UI design ethos. However, it looks like at least for now, third-party apps won't be able to emulate such design expansion--though we imagine that may be just temporary until the team comes out with the proper dev tools and standards.
Finally, Long Zheng correctly hints that the Metro team is still at work evolving the UI, something we also heard in Barcelona at the Mobile World Congress. Considering Microsoft has expanding Metro from Zune to Windows Phone to parts of Windows 8, there's little doubt we'll be seeing some interesting changes in the UI over the next few years.