I'm not a battery expert but I think the way it works at the moment is that after fully charging a battery, the laptop will trickle charge the battery. This is so that it alway stays topped up to 100%. Problem is that if you leave the batteries in all the time and never actually use them, then it will gradually screw up your batteries.

But from what I'm reading here, trickle charging an already full Li-Ion battery will kill it, so they should drop the charge to 0 instead of a trickle, not do something that'll fry the battery. It's not difficult for the charging system to query they type of battery in there, and if it's Li-Ion, don't trickle charge. And if you need a full change, either pop out the battery, and put it back in, or pull the AC out, and plug it back in to reset the charger to top off the battery.