Why DIDN'T the MacBook Air get the new 45nm CPU?

Intel launched their brand new 45nm mobile dual-core processors last week with 60% smaller packaging size.  Yesterday Apple announced their Über-sleek MacBook Air ultra-slim notebook which also uses a specially designed Intel dual-core CPU with 60% smaller packaging.  Naturally I assumed the new MacBook Air uses Intel's latest Penryn-class 45nm technology with low leakage hafnium metal gates and I called Intel for confirmation of this "special" processor.  I thought to myself: What's so special about it if every PC vendor can use the same shrunken CPU?

To my surprise, Apple didn't use the newest 45nm mobile processor with 107mm^2 die size; they really did use a "one-off" "Merom" 65nm 143mm^2 die designed-just-for-Apple CPU from Intel.  Intel specially designed a larger 65nm core with a specially designed package that's 60% smaller.  This means instead of using the latest 45nm processors that are faster and more energy efficient and are already that small without any special packaging, Apple got a "special" 65nm chip.

This begs the question why Intel doesn't make its new 45nm packaging even smaller than the current 60% reduction in size if it can reduce its packaging by 60% on 65nm technology.  It also begs the question why Apple had to go to the trouble of a tailor made 65nm part when the 45nm part launched 3 weeks before the launch of the MacBook Air.  Several other PC makers were already showing off their 45nm based notebooks last week at CES.

I spoke to a few people about this and asked for some theories and we came to a somewhat reasonable guess so I'll offer these up as some possible reasons.  For a product as specialized at exotic as the MacBook Air, the design would have needed to start some time ago.  When that design started, it may not have been a certainty if 45nm Mobile Penryn would be ready to ship with MacWorld and there may not have been working samples to start the design process.

Despite the fact that other PC makers have 45nm based notebooks ready to launch, none of them are this sleek.  So ultimately it doesn't really change the appeal of the MacBook Air and it will be the thinnest notebook on the market.  In 20/20 hindsight perhaps it would have been better if the MacBook Air had shipped with a 45nm CPU and maybe we'll see a quick refresh from Apple to the new processor since the size is obviously not a problem.  It's just that "special" in this case isn't a flattering thing when referencing the older CPU used in the MacBook Air, but the MacBook Air is still every bit special in a flattering way.