'tsLock O' Lets You Lock Your iPhone in Any Orientation You Want
Unfortunately, Apple only gives you the option to lock your device into portrait orientation. A new free jailbreak tweak dubbed tsLock O
by iOS developer typ0s2d10
allows you to lock your device into any orientation that you want to; including landscape orientation.
After installing the tweak, if you want to lock your device in landscape orientation, you will need to go into an application that supports landscape orientation, such as Mobile Safari, and then open the App Switcher. After you do this, swipe over to your iPod controls and tap on the orientation lock button.
The orientation lock icon will appear in the Status Bar even when you’re in landscape mode, and you will be unable to shift the device back into portrait orientation until you release the orientation lock via the App Switcher. The process is exactly the same as if you had set the orientation lock in portrait orientation mode.
TsLock O does not have any options to configure and the tweak is compatible with both iOS 5 and iOS 6. The tweak is available right now for free from the BigBoss repository in Cydia.