I work for a company that sells USB devices and provides drivers for them.
In Windows 7, you could install and use unsigned INF driver files for USB devices as long as they didn't add any code to the kernel. Our company uses generic drivers provided by Microsoft (usbser.sys and winusb.sys), so we never needed to sign our driver packages. You can see an example of such a driver package.
Based on a report from one of our customers and from another Stack Overflow question What changed in the driver signature requirements for Windows 8? and the Arduino forum, it sounds like the Windows 8 Consumer Preview has stricter signing requirements that require all third-party INF files to get signed. The error message people are getting when trying to install drivers that worked on Windows 7 is:
The third-party INF does not contain digital signature information.
What is the official word from Microsoft that confirms that the signatures will still be required in the final version of Windows 8? A sentence or two from MSDN.com would be sufficient, but I can't find anything.
I am considering buying a signing certificate, but before I pay $200 I want to be sure I will actually need it in the long term. It's possible that the new signing requirement is just in the consumer preview and not in the real version?
To answer my own question: Yes, the final version of Windows 8 does require all INF files to be signed, but you do not need to submit your drivers to the WHQL. I wrote about this requirement and much more in my article Practical Windows Code and Driver Signing.