http://www.macrumors.com/2008/10/15/intel-update-macbook-airs-get-penryn-macbooks-and-pros-get-montevina-benefits/
Intel's processor and chipset codenames have long been a source of confusion, and the adoption of NVIDIA's chipset in the newest MacBooks and MacBook Pros won't help matters.
One of the updates that had been long anticipated for the late 2008 MacBook and MacBook Pro updates has been the adoption of Intel's Montevina platform. This topic got lost with all the recent rumors of hardware redesigns and the adoption of NVIDIA's chipsets.
Despite Apple's migration to NVIDIA chipsets, Apple has still adopted the key advantages of the Montevina platform. This primarily includes a 1066MHz front side bus and the latest Penryn processors. How much of a difference (if any) the higher bus speeds have will have to wait for side-by-side benchmark testing, though the graphics performance of the new NVIDIA GPUs should give the new notebooks a clear graphical advantage.
This likely doesn't change anything for future planning as Apple will certainly adopt Intel's upcoming Nehalem processors over time. Nehalem is expected to offer a dramatic performance boost over existing processors. These next-generation Intel processors will be first launched for servers in Q4 2008, and come to desktop and mobile platforms in 2009.
Meanwhile, Intel confirms that Apple has quietly replaced the processors in the MacBook Air with the latest 45nm Penryn processors.
But new Intel processors did make a debut in the refresh of the MacBook Air. Instead of the Small-Form-Factor (SFF) 65-nanometer Merom chips, Apple has gone with with the more advanced 45-nanometer Penryn SSF processor. Penryn chips typically boast either 3MB or 6MB of cache memory versus the 2MB or 4MB that the older mobile procesors offer. (Cache memory speeds performance.)
The MacBook Air's processors now carry 6MB of cache memory (up from 3MB) and use a more power-efficient design. Apple had previously been using a custom 65-nm Merom chip. Any power savings from the new processors, however, may be offset by the adoption of the NVIDIA graphics card as Apple has not advertised any benefits to the change.