Alright, so we know about all the different locking apps out there. We're pretty much forced to install a 3rd party lock app because the default one is quite limited and makes you jump through hoops to do something that should be done by default - which is to lock when you turn your screen back on, without having to do so beforehand.
Well,
danielherrero (from XDA) has created a fix that will enable the default lock function to actually lock when your screen turns back on. So when your device goes to sleep or you press the power button, your screen will lock when you turn it back on. This is perfect for those who want to lock their screen upon wakeup, but don't need all the extras that come with s2u2 or any of the other locking apps.
Btw, I think the dev is also creating a version that locks the screen when you shut your screen off...
App has been updated to version 1.2. Now LockDevice has a settings menu that lets you easily enable/disable it and also lets you choose between lock on sleep or lock on wakeup.
Original XDA thread:
http://forum.xda-developers.com/showthread.php?t=542482