First it’s important to understand what overcharging is:
Over-charging occurs when the charger keeps the battery at a temperature that is warm to touch (body temperature) while in ready condition.
Li-Ion laptop batteries have built-in controller chips which prevent it from overcharging, as they can explode if overcharged. Overcharging does not affect the life span other than potentially destroying the battery.
A lithium-based battery should never be allowed to get warm in a charger. If you have this happen, the battery is no good or the charger is not working properly. Don’t continue to use the battery or charger if this happens.
A Lithium-ion battery may be damaged by extensive overcharging (continuously on a charger for more than 24 hours). Damage to the battery from overcharging would only occur in the very unlikely event of a malfunction of the charging system.

uhhhhhhhhhhhh huh........ do you want a medal?

my G7 and phones have Li-Ion batteries and i leave them on charge at home - no issues because they stop charging when there 'full' same as laptops etc

Well, in my experience with laptops and other rechargable stuff, leaving them plugged in all the time does seem to shorten the battery life (not a very scientific statement, I know). Li-polymer stuff doesn't like to be fully discharged either.

Can I have a medal too please apache :-D

Medals for everyone!

what is Overcharge? The forcing of current through a cell after all the active material has been converted to the charged state, that is, continued charging after reaching 100 percent state-of-charge.

resources:http://www.laptopbatterymart.com/battery-glossary.htm

Overclocking for batteries? Sounds about right - generating excessive heat, shortens life span etc if done wrong

Yes. Overcharging a lithium ion battery will kill battery life. It happened to my:

1. IBM ThinkPad T40 battery

2. Gyration Air Mouse

Don't overcharge your laptop battery,especially with older technologies,it's good idea to avoid overcharging your batteries everytime.Very hot or cold conditions can affect a battery's performance and in some cases can even cause permanent damage.Keep in mind that a laptop computer battery should be stored in a cool,clean,dry place when it is not in use.If possible,keep your rechargeable battery in the car with the heater or cooler running until you need it.

resources: http://www.buy-batteries.net/battery-laptop.html