Ipod comes with a battery that cannot be replaced (easily) by the owner. Believe it or not EVEN Ipod competitors are switching to this type of non-user-replaceable battery. Go figure

I just bought a Cowon X5 and its battery cannot be replaced by the user, you have to send it in. There is a "change the battery" warranty. If you try and do it yourself it voids the warranty Ipod is similar.