I just upgraded to gentoo-sources-3.2.9 from 3.1.1 only to find out that my logitech wireless mouse stopped working. It was correctly detected as a usb device but no input device was created for it:
Bus 005 Device 004: ID 046d:c52b Logitech, Inc. Unifying Receiver
After some Googling and looking around kernel settings I found out that I had to enable Device Drivers -> HID Devices -> Special HID drivers -> Logitech devices -> Logitech Unifying receivers full support. Hopefully this information helps other Gentoo users who run with most things disabled. Updating the kernel with make oldconfig I did not notice this option because I have had CONFIG_HID_LOGITECH disabled and it hasn’t caused any problems.