Do the iPod Touch 2nd and 3rd gen have the same batteries?
Are the batteries the same? Or maybe just the same between the 2nd gen and the 8gb 3rd gen?
Between the 2nd and 3rd gen 8gb all parts are the same, and that includes batteries, but I believe that the battery on the 3rd gen for the other capacities is slightly thinner than in the 2nd gen.
According to the teardowns you can get these descriptions:
The battery. 3.7 V Lithium-ion polymer, as expected. Apple part number 616-0404. No word yet on the mAh rating.
The battery. It's 2.92 Whr, which comes out to be 789 mAh.