I had Kernel 2.6.11.4 running with a udev system and my cdrom could be accessed as user in the cdrom group without any problems, after upgrading to udev-079 I didn't have the permission any more to access the cdrom and also only saw the it as a dvd device and no cdrom or cdrw devices where shown. After upgrading to kernel 2.6.15 everithing works fine again.
We don't care much about 2.6.11 kernels, latest x86 stable is gentoo-sources-2.6.15-r1.