I am using the utility (Mini Battery Logger) mentioned in the Macinhack article "Getting the most out of your battery". My battery has been through only 37 cycles, but my MBP seems to have a lower on-battery lifetime than I would expect -- only a little over an hour.

According to Mini Battery Logger, I have a capacity of 24% of new, and the estimated date of death is (was?)June 23 5,877,610 years ago, but the overall rating is "good". *cough*

I ordered one of the FastMac "High Capacity" batteries.