Just a couple of days after there were rumors that Google Allo will be released sometime this week, the smart messaging app has started rolling out - it's at-least available to download/install for Android users in India. Reputed leakster @evleaks had said that the app will be launched on September 21, and looks like that's precisely what has happened. Users in the US, however, are currently seeing a pre-register button on the app's Google Play page, but we expect that to change soon. In case you don't already know, Allo - like Duo - also uses your phone number to find your friends...
Source: http://www.gsmarena.com/allo__googles_smart_messaging_app__starts_rolling_out-news-20627.php