The initial model of the Rift is centered around getting an ideal PC environment with currently trying to iron out the few issues with the development kit for consumer release. But they're already stated they want to have Android support in the near future with it but as secondary goal once they're done their first initial release. This will allow for using the same device on both the PC and with your Android device of choice. Given how fast the phone/tablet market evolves these days, it makes more sense to me to have the VR device independent of the Android hardware. The GameFace sounds nifty, but it'll quickly find itself with outdated hardware running it, while the Rift's model of having it connect to your phone will allow for updating the hardware as new devices come out. I'd much rather buy a $300 VR display that can be used for years with new phones than having one that is locked into a specific GPU/CPU built in.