Read what Apple has to say about notebook batteries:
- Apple’s Batteries Page
- Apple’s Notebook Batteries Page
EDIT for the lazy(es) who don’t want to read the links:
- lithium-ion batteries need to be fully discharged and recharged at least once a month. Go ahead and create an iCal reminder…
- Leaving it plugged won’t affect it, as long as you remember to do (1) every 30 days.
- If you have to “store” and put your battery away for more than six months, you should definitely store the battery with a 50% charge. Reasons are listed in the corresponding link.
- Pay attention to temperatures, they can damage and severely hamper battery operation.
I hope this makes everybody happy.
Now… as a final note: the new unibody stuff coming from Apple doesn’t have removable batteries, however, the battery design is the same… those are lithium-ion batteries, no matter how fancy they make it look. Macbooks do not have a nuclear core in there, so the same rules apply, except that… well, you can’t remove it for storage, so more than ever, remember the 30 day rule.