If I understand correctly, the Tor client works as a combination of a proxy server and application plugins (such as the Firefox Torbutton) that enable use of the proxy and contain additional application-specific privacy features (such as suppressing cookies, sandboxing JavaScript, turning off Flash).

That works very well with applications that support it (such as Firefox). But is there a way to establish a VPN over Tor, so that my whole Wifi network can be protected, including applications that do not support proxy configuration and devices like iPod touches?