The only truly revocable permission for applications is internet access. Each application runs as its own user (although some from the same publisher do use the

The only truly revocable permission for applications is internet access. Each application runs as its own user (although some from the same publisher do use the same user), and this can be combined with the linux kernel's firewall to prevent internet connections to specific applications. To do this you need root access, and an application like DroidWall. By default, DroidWall only allows applications you select to have internet access. Since DroidWall is using the kernel's firewall, it doesn't need to do anything in the background, so doesn't impact battery life.