I find it really hard to believe the conspiracy theorists who think Apple is doing this to force decreased battery life upon the masses as a method of selling more replacement hardware. I mean, their logic makes sense, and frankly I'd prefer using Apple's compact 85W adapter with this type of functionality to them pushing a larger, bulkier adapter for those rare times that the entire system is running at full capacity. Adapter efficiency under extreme heat also factors in...
The point of this article is not that Apple notebooks are constantly sucking on the battery even when plugged in. It is that occasionally when your 2.8Ghz processor, 15" screen (brightness cranked), 9600 GT, and 7200RPM HDD (the Macbook Pro's top configuration) are all running at max capacity, you may need to use a bit of the batteries power, and Apple has taken steps to ensure your system doesn't shut down. What other notebook fits that kind of capacity into an 85W envelope anyway? Most others, comparably configured, would ship with a bulky-as-hell 120W which, believe you me, is not something you want to travel with, a fact which entirely eliminates the advantage of the Macbook Pro's design.
Yes, Apple could have designed the functionality better. Spikes in power demand are certainly hard to detect in time to prevent a shutdown, but not so hard that this functionality should be turned on all the time, regardless of load. However...
While a lot of you may not like Apple, that shouldn't spur you to stretch every bit of negative press into a conspiracy based on ignorance.