QuickSMS is an SMS client that runs inside SpringBoard eliminating the need to wait for an SMS app to load.
Ever get a text message when doing something on your iPhone and you want to reply, but don’t want to go back to the SpringBoard and load up the SMS app. Quick SMS is the solution to that problem. Quick SMS is a replacement for the SMS app which is accessible from any other application simply by pressing your volume up button. The app will swoosh onto your screen to let the texting commence.
Sending a text is the same as usual but you’re given more features not found in the default SMS app, Emoji icons, emoticons, delay timers, encryption, contact, note, and template insertion. Once you’re done, simple press the volume down, or home button to close it.
[Source - BigBoss] Cydia