For those complaining that the MBAs are still using 2008 CPUs, here's what Anandtech has to say:
I'm not saying C2Ds are better than iXs but this shows that there is an advantage to using very mature technology that, although technically the same as it was two years ago, is built much better now.
The old MBA is actually slower than the new 11-inch, despite the advantage in CPU speed.
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The 45nm process these Core 2s are built on is as mature as it’s going to get. I’m guessing yield on these parts is as high as can be and as a result, power consumption is probably consistently lower than the original 1.86GHz parts Apple shipped back in 2008. The peak thermal specs themselves haven’t changed, but the actual power characteristics have.
I'm not saying C2Ds are better than iXs but this shows that there is an advantage to using very mature technology that, although technically the same as it was two years ago, is built much better now.