I think what everyone is missing here is virtualization, why do you need your phone to have the power for it run them locally. Keep all the heavy lift action in the data center and with the new mobile data speeds "stream" your desktop through the phone onto a local screen/interactive devices.

Phones will be like thin clients (a la citrix receiver) and so we have persistent backups and universal access along with desktop performance but still portability and battery life when not in thin client mode.