No official word on when it will release to the rest of the world, but presumably very soon thereafter. In some ways the Tango update is very much "the Nokia update"; Nokia’s bread and butter has long been lower-cost phones in developing markets, and by enabling Windows Phone to run on less powerful hardware they are really playing to Nokia’s market strength.
Of course in the Chinese market, at least, their work will still be cut out for them; While Nokia was at one point the largest cell phone maker in China, Android has grown quite popular there (both “regular” Android and forked Chinese versions) and Apple’s iPhone is a much-coveted item. Will Nokia and Microsoft be able to gain a foothold in the largest mobile market in the world?
We’ll keep an eye on it, but for Windows Phone to succeed it needs desperately to start gaining market share somewhere.
source: Tech Crunch