Royceee - You can't expect the battery to last for 3 years and still run like new. There is a reason that manufacturers only warranty the batteries for 1 year. Rechargable batteries lose performance over time, you can't avoid this and this is not due to "memory".
Lozza - Replacement batteries probably run about $100. This is what most companies charge for an extra battery when they sell you the laptop, but I have never actually had to buy a replacement battery, as this is my first laptop. As for the charge level at which to store them, it doesn't really matter. Probably you or someone who told you confused Li-Ion batteries with NiMH batteries, which need to be stored with at least %40 charge. If you think that you need further information on how to store them, I would consult a manufacturer of Li-Ion batteries (I think Sanyo makes some).
Nootrak - This jump in battery life is to be expected. The voltage that comes off a battery is actually not constant. Batteries start out with a higher voltage that then decreases an plateaus for a while, and then drops off. See the following graph -
Since your laptop measures the battery voltage to calculate battery charge, abnormalities like the one you are experiencing are caused because whatever program they use to calculate the charge can't perfectly match the actual voltage curve. This is perfectly normal.