I am currently considering update my second generation iPod Touch to the 4.0 firmware (not 4.0.2 because I need to jailbreak it). I know that if I update the firmware, I will lose the jailbreak. But is it possible to update it without losing music/videos/apps/etc?
All the instructions I found involve going into DFU mode, and afaik, you lose all your songs/data when you go into DFU mode.
I have my SHSH on file with Cydia, so that is not a problem.