I've had the same power management issue for my non-Retina mid-2012 MBP. The main issue is that the machine insists on doing something whenever AC power status changes. Even if the machine is asleep, it'll wake for 10 seconds or so and then sleep again. Even if you change the appropriate pmset flags, which is unnerving, because those flags are now being ignored. The best way to reproduce is to take the sleeping MBP, unplug it, open the lid, and begin using it. BAM, it goes to sleep on you!
The problem appeared either with 10.8.2 or a firmware update that arrived around that time. There are a couple Apple support threads about it, and I've done everything (yes, I've reset the PRAM).
I can confirm having this problem too. The reason the system powers back on when you change AC status is because of the Power Nap feature, but you're right, even when it's completely disabled, and even when you adjust pmset to disable 'safe sleep', it still happens.
The problem appeared either with 10.8.2 or a firmware update that arrived around that time. There are a couple Apple support threads about it, and I've done everything (yes, I've reset the PRAM).
I hope it gets fixed soon.