I am running the rawhide kernel 2.2.13-09 with a RH60 system. On all 4 of my Linux boxes it replaced the kernel with the one on the CD. It however did not replace the kernel-source or the IBCS.
Just to clarify, did the upgrade actually delete the new kernel or just replace its entry in lilo.conf? We have fixed the problem where the entry is replaced in lilo.conf in the latest internal code, but if you are actually seeing the upgrade delete the new kernel, then please reopen this bug and we will try to replicate in the lab.