there are operating parameters that Intel goes by and they don't want anyone going outside of them.
In other words "Use at your own risk", but not with Intels blessing, or Apples for that matter.
But I would think that by undervolting your effectively turning the chip into a ULV.
If this is actually what is going on (I haven't a clue) then this is a really desirable modification .(just what we want)
I wouldn't say you are turning your chip into a ULV one... but it will improve things. The idea is that all Intel chips must work within a certain specified voltage range. They test all chips to make sure they work in that range. Some will work within a wider range... and that is why undervolting works. This is why you must test the stability when you use Coolbook... every chip will have a different threshold.
As far as why Apple won't do this themselves... do you really think Apple is going to retest the thresholds of every CPU? It would be way too costly. There is no notebook manufacturer I know of that directly supports undervolting. Just because they don't support it, doesn't mean it won't work. It's just like overclocking... accept the risks if you want to tweak... and be aware of the possible ramifications.
I wrote the author of Coolbook to ask him if he could lower the available voltages even further... but he never responded... based on the success people are having with CB... i think many people could get to even lower voltages.
Another thing to remember is that the screen backlighting is one of the biggest power draws on the laptop that you have direct control over. Turning the brightness down to the lowest acceptable level is the best way to conserve battery life.
Sean