Found this program call iLock in MotorolaFans.com Forums, It sort of similar to the slide lock like iPhone.
I installed on my Sony Ericsson P1i and it works fine.
Since it’s a full screen java app, it doesn’t really key lock the screen, holding the back button still bring you to the main screen.
When you unlock, the application will quit. So to launch iLock, it take a couple of seconds to get the locked screen.
Edit: Didn’t realised that my link was broken, I have uploaded it here: IPhoneLock
For those who still downloading this old Java version, the author has released the iPhoneLock in UIQ3 native SIS. Here’s the new entry on that.