Yes, the Intel i7-620M processors are better for the battery because they use the new 32nm transistor, which are more power efficient than the 45nm transistors (found in the i7 QMs).
After thinking about it, using the 620m might actually be better for those who plan on using the MBP mostly on battery. From what I've heard, the QMs have an issue where they stay at their default frequency and run on one core when they are unplugged. The 620m won't be affected by that, because their default is at 2.66hz, much higher than the default frequencies of the 720qm and the 820qm.