dmack, it seems that there everyone does it differently and there are a million ways to do it after doing a Google search, so I will just tell you what I did:
1. Insert battery, charge phone powered off until light turns green
2. Go into recovery, ->advanced ->wipe battery stats ->yes (Whenever I wipe something in recovery, I usually do it 3 times, just to make sure)
3. Power up, make sure the phone is at 100, then use the phone, letting it completely drain until it's off
4. Recharge it powered off until the light is green
5. Repeat steps 3 & 4
Again, I don't know if that is right or if that's the proper way to calibrate it, but it has done wonders for my phone so far. I was struggling to get 6 hours before and now I'm doing much better (haven't counted), but I really think I should have been paying more attention to wiping battery stats and calibrating when I flash a new rom (I've flashed dozens of times, never once re-calibrating). Have fun and enjoy!