Battery bloat?

I've been reading several articles and reports about "battery bloat" in older Macs and iPhones. I noticed that most of the victims were iPhone 3GS, but some pages I read insinuated that this is something that happens to all aging lith-ion batteries. So is it something that is going to happen to every iPhone sooner or later? Is there any way I can prevent this from happening to my two year old iPod 4G?