Some of the conventional wisdom about maintaining rechargeable batteries, ain't so wise for newer Li-Ion batteries.
As you can read on my battery page, Li-ion batteries need a very different kind of care than the old, heavy Ni-Cds and Ni-MH batteries did.
These suggestions only apply with Li-ion batteries. These are the lightweight ones that are custom-fitted to your phone, laptop or camera. They have weird voltages like 3.7V or 7.4V. These are the dedicated batteries used in all modern digital SLRs like the D80, D200, D2X, D100, D50, D70s, Canon 20D and any point-and-shoot that takes a dedicated battery. Hint: these batteries will be marked "Li-ion."