You guys realize core 2 duo is 2+ years ago processor that still ran on DDR2 along with OLD Intel architecture.
The memory controller is not in the CPU in Core micro-architecture, thus the CPU does not determine the supported memory. DDR3 support has been present since the release of ICH9-M, which was released in late 2008. Core 2 Duo Macs have been using NVIDIA chipsets since late 2008 though but the DDR3 support came around the same time (MCP79 chipset).
The guts of the MBA are completely upgraded. From DDR2 to DDR3 (not to mention rumored upgradeable this time up to 8gb up from max 4gb)
Current MBA's hardware supports 8GB of RAM already, Apple just doesn't offer that.
The motherboard chipset is upgraded to work with the new processors increasing throughput from every interface such as SSD etc.
SATA is the only interface that will get an upgrade. USB is still USB 2.0 and PCIe is still PCIe 2.0.
And for those who thinks nvidia 320m is better than intel HD3000 then think again! Intel HD3000 is IN the i core with higher clock speed and much faster bus speed.
It's not like the PCIe x16 slot isn't enough for the 320M. HD 3000 being in the same die has nothing to do with its performance. Benchmarks show that it will most likely end up being slightly slower than 320M.