As far as I know, a swollen battery is a manufacturers defect and is a hazard to the machine and the person using the machine. If you call Apple Care or take that machine to a Genius bar, it was common (when I worked for Apple Care and then as a Genius) to replace those batteries in or out of warranty. It was never before referred to as "normal/expected behaviour". When a battery no longer holds a charge, I completely understand having to pay for a new one. When a battery just starts expanding one day (from no fault of my own), it is considered a defect and should be replaced without question as this was a defect with the manufacturing process and has nothing to do with the life of the battery.
I spoke to a tier 2 agent and a manager at the Apple store and they both told me that it is normal behaviour for a battery to swell. I can't even describe how livid and disapointed I am with the support I received today and the change in Apple's stance on defective batteries.
So, does anyone from Apple want to give a reason why this is "expected behaviour"? This would mean that these batteries are designed, by Apple, to fail in that manner if this is expected. If not, then it should be considered a defect. So Apple is stating that these batteries are designed to fail and potentially damage your $1000+ machine.
So, this brings me to the question, if this is a design flaw and not something that has been designed into the battery by the engineers, why is this design flaw not fixed by now? If this can severly damage a machine (from pushing on the internal components), why is this not being taken more seriously?
I await Apple's response on this.