Ryan Petrich has released IconRotator, a new tweak that will rotate our SpringBoard icons accordiong to the devices orientation. IconRotator works with icons and folders but it wont change is the swipe orientation. When device is in landscape, you will need to swipe from bottom to change pages.

IconRotator is available in Cydia via Ryan Petrichs repo: http://rpetri.ch/repo/

Source [FSM]