Here's the run-down:

3 month old battery, 2 .5 year old machine (PBG4 1.67, 1.5Gram).

I'm careful to drain the battery fully more often than not and I'm careful to keep it well stored. As of this week, a full charge only registers as providing between 39-48 minutes of power; the week before it was roughly 2:43 at full charge.

A) What gives? This is almost a brand new battery.
B) What software, resets, or Mac-magic can possibly help me in this situation?

I have reset the PMU (power-down, remove all power, hold power button for 5sec), re-calibrated (again, something I try to do at least once a month), but I still have the same lack of time on my system.

Any and all help would be greatly appreciated.