One of the features you may seek about it on the official Facebook app is how to save Facebook photos on your iPhone camera roll. Now we got it, FBPhotoSave is a new Cydia tweak which allows you to save photos from Facebook app directly to your camera roll.
How to use FBPhotoSave? simply tap and hold the picture you want to save until it prompts from you to save it as shown on the above screen-shots.
FBPhotoSave is now available via Cydia under ModMyi repo for $0.99