CamVolZoom allows you to use the volume buttons to zoom when recording photos

  CamVolZoom is a tweak released during this evening in Cydia, and with its help we can modify the functionality of the Camera application during its use to record pictures. Tweak- allows us, after installation, to use the volume buttons to zoom in/out, they are normally used to record pictures. The tweak is compatible with the native Camera application and with other third-party applications from the App Store, and through an iOS menu we can set the distance for which the zoom is made or how long it takes to do it.

Compatible with iOS 5 and 6, iPhone/iPod/iPad with Camera. Works in Camera app, Lockscreen Camera, iMessages, Kamera, InstantCamera and BiteSMS. The new way to zoom the camera! Use your volume buttons, the one in "+" sign for zoom in, the "-" sign for zoom out. Hold the volume buttons for continuous zooming. Properties like zoom adjustment amount, delay, slider animation duration etc. can be set from Settings > CamVolZoom.

  CamVolZoom it is available for free in the repo BigBoss al Cydia.