The MCP89 is the chipset that has been used in older MacBooks as well as the new MacBook Air. Apple’s use of this NVIDIA chipset limits its choice of processors to the previous-generation Core 2 Duo. This tradeoff allows Apple to incorporate the faster integrated graphics cards from NVIDIA in these low-end machines. According to NVIDIA’s CEO, Apple plans on continuing to use these older chipsets for some time.
I use a 17-inch MacBook Pro with a 2.8GHz Core 2 Duo CPU. Sure it’s last-generation, but I don’t feel the need for a faster CPU. The gating factor on my MacBook isn’t the CPU. Nor is it the GPU: I use the integrated less-powerful NVIDIA GeForce 9400M 99% of the time. The fan kicks in less often and I get much better battery life. If I played games that required more graphics power I’d turn on the discrete 9600M GT, but I don’t play games much. I think the real gating factor is the hard drive. I bet the tiny 11.6-inch MacBook Air with a 1.4GHz Core 2 Duo and SSD boots up faster than my MacBook.
You don’t need the biggest and baddest hardware to run things fast. The iPad is a great example: it has a puny A4 chip (puny compared to a 2.8GHz Core 2 Duo) but it runs like a champ. Why? Not because it has so much power, but because things are efficient. iOS is nimble. Flash storage improves app launches. Even the apps are optimized.
What if Apple kept slimming down OS X? What if Lion, the next release of OS X, was even smaller and required less hardware resources than Snow Leopard? What if applications written for Lion were leaner? Would we need a faster CPU? Nope.