FullForce is a new jailbreak app in Cydia to force your iPhone sized apps  in fullscreen ipad resolution without pixelizing it. FullForce doesn’t work with all applications.

Some apps don’t like it or will not respond to it. It works best witht text based apps  such as  Facebook twitter and Stanza. It does not do well with games.  FullForce is available from Cydia for free. Once installed, select the applications you want to toggle ON/OFF in theSetting/FullForce.