S2U2 (Slide2Unlock2) is a simple lock/unlock application which has the iPhone style slide unlocking. It can be used as a screensaver while you don’t use your device. It has a CallerID function (but some devices may not work, so please try it first); S2P control plugin; and volume control.

Changes:

– renamed “InCall Lock” to “Lock on Talk”; additional option for using external power; and moved to S2U2 Settings -> Power.
– added option – “Don’t lock system”; when it’s on, the system will behave the same as the old version. (S2U2 Settings -> Advanced)
since v2.20, when S2U2 locks the system, the system will behave as it’s locked by the system built-in lock.
however, on some devices, it may lead to some not-welcome behaviour when locked:
for eg, on Omnia/Omnia II, the backlight will be dimmed; on some devices, unlock will always go to the home screen.
but there is a draw back when this option is turned on: some keys or system functions can be activated even it’s locked.
– added to show the divert call status on the lock screen.
– a few minor bugs fixed.

http://forum.xda-developers.com/showthread.php?t=527523