Looks like we missed this tweak hitting Cydia. MessageHeads is a great tweak well worth the buy. It gives you the ability to quick reply on the lock screen with a passcode, and looks cool in the process.
The tweak is based off of how the messages looks in the Facebook app. It over all has a smooth feel and it is easy to use. For now this is the best quick reply tweak we have. So get to Cydia and get MessageHeads today.