It's true. This feature has been axed for all mac laptops before late 2008 ones.
That is funny you started this thread, I was just about to when I noticed the same thing. It is weird Apple took this feature out.
Perhaps Apple removed this in the late 2008 laptops. I have an aluminum MB. Never noticed this on my iBook.
I don't see what did big deal is, all the "better battery life" setting did was change the amount of time before dimming/turning off the LCD, and the sleep timer. It never actually changes the CPU/GPU clock or anything like it did on the G4/G5.
Mine in 10.5.5: