With little fanfare, Microsoft just announced that the xX64 version of
Windows Vista will
require all kernel-mode code to be digitally signed. This is
very different than the current WHQL program, where the user ultimately
decides how they want to handle unsigned drivers.
Vista driver developers must obtain a Publisher Identity Certificate (PIC)
from Microsoft. Microsoft says they won't charge for it, but they require
that you have a Class 3 Commercial Software Publisher Certificate from
Verisign. This costs $500 per year, and as the name implies, is only
available to commercial entities.
Also, drivers must be signed for devices that stream protected content. This
includes audio drivers that use Protected User Mode Audio (PUMA) and
Protected Audio Path (PAP), and video device drivers that handle
protected video path-output protection management (PVP-OPM) commands.
News source: OSNews