In a rare occurrence, the processor speed of the laptop is actually reduced, from 2.1Ghz to 2.0Ghz. It's not exactly relevant though, as the machine got a much more powerful graphics processor: from the GMA X3100, to the NVIDIA's 9400M architecture, which will surely bring a serious graphics boost to Apple's cheapest laptop. In addition, the default configuration receives a doubling of memory, from 1GB to 2GB of DDR2 SDRAM.
Of interest is that the laptop retains its FireWire 400 port, despite the fact that the pricier unibody models lack the port. The upgraded white MacBook lacks the Mini DisplayPort, the connector Apple is standardising upon, retaining mini-DVI instead. Pricing remains the same.
On a related note, Apple also released QuicTime 7.6, which offers several security and bug fixes, for both Windows and Mac OS X.