You can build your own backup battery if you're feeling adventurous!
http://www.drewperry.co.uk/iPod/inde...ge=batterypack
and
http://www.chrisdiclerico.com/mt/archives/001572.php
I personally have a 3G 20gig and I think it is safe to say that my battery isn't lasting as long as it should. I get about 4/5 hours before it dies. At the moment it isn't too much of an issue since I can usually recharge each evening. The benefit of having all of my music in a cool little gadget far outweighs the battery problems for me, IMO.