(Not a new discovery, just a refinement) **
Since the latest update to 1.4, I found and easy fast and foolproof way to unlock the lock screen. I have a Sprint Pre, but this should work just as well on the Pre Plus.
After touching the power button, simply place you finger on the center button and swipe up to the lock icon.*
*This works every time and is the quickest and most efficient way to unlock the screen. Enjoy! *