Since Macs use pretty much standard components now, Apple are probably just bundling the vendor's drivers for Windows use. My father for some reason (and against my advice) purchased 64-bit Vista with his new computer and is always complaining he can't find drivers for hardware, so I can fully believe that some of the hardware lurking inside the Mac range only has 32-bit Windows drivers available. Apple aren't going to spend effort getting 64-bit Windows drivers written as the main purpose of Boot Camp is to allow those who have previously used Windows to purchase a Mac yet run their old software.