New tweak in Cydia LSRotator. This tweak lets your iPhones lockscreen rotate according to your devices orientation when you flip your device like iPad

Following SBRotator, this tweak comes now to fill the gap and lets your use your device in landscape at the loockscreen too.

You can lock orientation if you wish,by simply tapping the locksreen with 2 fingers.
Rotation duration,orientation angles and graphical options are available under settings