Theres a few programs in Cydia or Rock that backup apps. The one in Cydia is Aptbackup and the one in rock not sure if its the same or a different one. I haven't read any into them to know the details on what they can and can't do.
When 3.2 for the Iphone comes out wait 2-3 weeks for the new jailbreak to come out. The developers need some time to get a jailbreak working right after that. Apple is outnumbered on preventing jailbreaks, lol. But you will lose your jailbreak when you update.