Yes, many lockscreens have this feature included. Some have an invisible slide to unlock and some have invisible tap to unlock.
You could install "Invisible tap to unlock" in Cydia. I have all the repositories on my phone, so if it doesn't show up for you, first install Stefwiz's repository and then All repositories and search again.
Yep, that's it, I knew it had to be there somewhere.
"Un-Unlockable" makes the slide to unlock graphics/text invisible, but it still functions like it normally would, just slide your finger across the bottom of the screen to unlock.