I've jailbreak my itouch (16GB). it is for sure the warranty is void. However, is there any way to restore it to its original state and e service tech at apple can't tell. regards
Restore in iTunes. That's it. I know this for a fact because I had an iPod Touch modded to the hilt and needed to send it in. Fresh Restore in iTunes was all it took. Apple serviced it without question.
I brought my hacked ipod in after the battery stopped working (it lasted around an hour at best). When i switched it on the person said 'oh, its jailbroken, cool!', took it, and gave me a fresh one. This was less than a week after i bought it though, so I would just say you should restore it with iTunes, so it leaves no trace behind.