I'm a little confused, some are talking like the "new power chip" is already out there ... is it? is there a serial number or part number that would indicate this "new power chip?"
According to the Google Groups link earlier in this thread, the new power management chip will be used for "future variants" of the Nexus 7. They probably changed the chip out for the 32GB models and/or future iterations of the 16GB models. It's possible they needed a larger-capacity control chip to handle the 32GB variant, or they found a cheaper chip and re-did the assembly of future models to use that chip to save money (or perhaps both).
In any case, this was a warning to people who build out Android ROMs. The driver for the new chip appears to be backward-compatible with the current chip, but it sounds like you'd have to backport the driver from 4.1.2 if you wanted to use 4.1.1 as a basis for building out a ROM that might end up on one of the devices that use the new chip. Chances are, there's no user-visible difference in functionality between the two chips.