LiON batteries: don't leave them fully charged

A SciAm review of LiON batteries mentions that leaving them fully charged shortens their lifespan:

... batteries degrade, but lithium-ion cells erode faster when highly charged and warm; an average notebook battery kept at full charge at 25 degrees Celsius will irreversibly lose about 20 percent of its capacity a year...

So it's better to let them cycle completely before recharging. Leaving the device continuously plugged in (like our Nano) will shorten its lifespan.