No, you cannot. When you modify the device in any way, your warranty is voided. However, if you restore the device, an Apple Store employee may not be able to tell that the device has been jailbroken, should you ever need to have it serviced.
How is there gonna be a way around this?
What does JAIL BREAK MEAN?
UUUUH HACKING THROUGH SOFTWARE?!
Do you think Apple is gonna want your JB touch
with all the illegal crap that isn't allowed on it? don't think so!
It is true your warranty is void when you jailbreak, but from experience with 1st gen iPOT if you restore to factory settings and restore original firmware they will take it back and replace if within the given first year after purchase.
Lucky! I want to exchange mines and make up an excuse y I need a new one but the warranty expired. If I were to return it I would say my uncle gave it to me and since I don't got AT&T I use it as an iPod. But again, the warranty expired