It looks very much like Apple will be giving birth to new MacBooks tomorrow, complete with the latest 'Santa Rosa' Intel chipset.
The latest iteration of Mac OS X - 10.5 Leopard - released on Friday - has drivers for Intel's latest-gen GMA X3100 integrated graphics solution.
Read: our review of Intel's GMA X3100
The GMA X3100 was part of Intel's 'Santa Rosa' refresh for its Centrino offering. This revision saw the MacBook Pro line gain new underpinnings. It's possible that the MacBook line will adopt this, too, replacing the Intel GMA 950 graphics in current models. Processor speed bumps are also likely, according to MacRumors.com
Apple last updated the MacBook in May.