nVidia communicates the supported memory limits on the GeForce 9400M chipset that fuels the new MacBook and MacBook Pro : 8GB maximum, 2×4GB DDR3 sticks.
Apple specifications is 4GB (2×2GB DDR3 sticks), but since Leopard runs in 64bits mode on MacBook & MacBook Pro it is still possible that 8GB may be recognized, we will have to check it 
Apple claims, in the MacBook and MacBook Pro specifications, that the maximum supported memory is 4GB.
On the past Apple claimed that first MacBook Core2 Duo are limited to 2GB albeit they support 4GB, recognizing 3.1GB. Same story for Core2 Duo MacMini.
And on other model such as the Core2 Duo iMac, the EFI BIOS limit memory use to 2GB albeit the chipset support 3GB or more.
The nVidia chipset that includes GeForce 9400M on both MacBook and MacBook Pro support 2 DDR3 ram-modules. These module have a capacity that range from 1GB to 8GB individually (4X the DDR2 SoDIMM ram-module capacity).
Theorically, we could put up to 16GB (2 modules of 8GB each) into the new MacBook and MacBook Pro, nVidia doesn’t state any limit other than the number of modules, and the CPU in the compatibility list supports all more than 4GB (at least 64GB) RAM.
So my asking is: did Apple limits its new laptop to 4GB by the EFI firmware, exactly as the old iMac GMA950 “Education”, or is it possible to have 8GB or even 16GB RAM on these new MacBook and MacBook Pro?
I wonder specifications where just false, as usually, and 8GB may give a huge boost to a MacBook Pro using VM (Parallels, VMware Fusion or even open-source VirtualBox), on video edition, photo library management…