http://www.droid-life.com/2015/07/17/cortana-for-android-leaks-early-available-for-download/#more-170981
I will say that this beta version caused my LG G2 on 5.0.2 to randomly turn off and reboot one time before I uninstalled it. It did work the few times I tried the app. But, it seems to be a far cry from OK Google.
