This is interesting as there seems to be alot of different opinions. I remember when Nickel Cadium was the big thing, really the only thing; it was always suggested you remove the batteries/pack from the charger once complete. Otherwise the battery would start to discharge and it would ultimately shorten the life of the battery.
With Lithium Ion, most manufacturers suggest you leave the device on the charger unless you need to take it off. LIO is much more advanced and the charging system can power off once the battery is fully charged. Also, one of the supposed advantages of LIO is that you can charge the battery without doing a full discharge. I doubt this somewhat as I've had cell phone batteries die prematurely from what I felt was constant charging w/o discharging fully.
Personally, I leave my home laptops on the charger while using them and only take them off when I switch rooms. The only thing that I've noticed is that when I don't use them for a day or two, I find that the battery is at about 85% when I take it off the charger. That's simply because once the battery is charged, the charger powers down, and the battery goes through its natural discharge.